TRACE · ROUND 4

A benchmark in which language models design roller coasters that RollerCoaster Tycoon 2 builds, tests, and rates.

claude-fable-5-1 · 20260902-fable51-design-full · round 4 back to model →
events
46
tool calls
33
rejected
0
session
0:00
Session trace

  1. I'll load the coaster tools, then plan and build a closed-circuit twister quickly to bank a score early.

  2. ToolSearch
    {"max_results":11,"query":"select:mcp__coaster__new_ride,mcp__coaster__place_piece,mcp__coaster__place_pieces,mcp__coaster__valid_next_pieces,mcp__coaster__piece_geometry,mcp__coaster__undo_piece,mcp__coaster__get_state,mcp__coaster__finish_and_test,mcp__coaster__best_result,mcp__coaster__demolish,mcp__coaster__screenshot"}
  3. piece_geometry
    {"dir":0}
    {"deltas":[{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":0,"piece":"flat","slope_out":0},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":0,"piece":"end_station","slope_out":0},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":0,"piece":"begin_station","slope_out":0},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":0,"piece":"middle_station","slope_out":0},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":16,"piece":"up_25","slope_out":2},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":64,"piece":"up_60","slope_out":4},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":8,"piece":"flat_to_up_25","slope_out":2},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":32,"piece":"up_25_to_up_60","slope_out":4},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":32,"piece":"up_60_to_up_25","slope_out":2},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":8,"piece":"up_25_to_flat","slope_out":0},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":-16,"piece":"down_25","slope_out":6},{"bank_out":0,"dir_out":0,"dx_tiles":-1,"dy_tiles":0,"dz":-64,"piece":"down_60","slope_out":8},{"bank_out":0,"dir_out":0,"dx… (7397 chars)
  4. new_ride
    {"dir":0,"ride_type":51,"x":60,"y":60}
    {"cursor":{"bank":0,"dir":0,"slope":0,"x":60,"y":60,"z":112},"ride_id":0}

  5. I'll lay out the ride: lift up at y=60 heading west, a big drop into a vertical loop and corkscrews, a banked 180° turn east, a return leg with hills and S-turns, then banked turns back into the station — all placed in one batch.

  6. place_pieces
    {"pieces":["begin_station","middle_station","end_station","flat_to_up_25",{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},"up_25_to_flat","flat_to_down_60","down_60","down_60","down_60_to_down_25","down_25","down_25_to_flat","flat_to_up_25","left_vertical_loop","down_25_to_flat","left_corkscrew_up","right_corkscrew_down","flat_to_up_25","up_25","up_25","up_25_to_flat","flat_to_left_bank","banked_left_turn_5","banked_left_turn_5","left_bank_to_flat","flat_to_down_25","down_25","down_25","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat","flat_to_left_bank","banked_left_turn_5","left_bank_to_flat","flat_to_right_bank","banked_right_turn_5","right_bank_to_flat","s_bend_right","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat",{"speed":10,"t":"… (1318 chars)
    {"circuit_closed":true,"cursor":{"bank":0,"dir":0,"slope":0,"x":60,"y":60,"z":112},"placed_this_call":71,"total_placed":71}

  7. Closed on the first pass. Testing it now to bank a score.

  8. finish_and_test
    {"bounds":{"max_tile_x":63,"max_tile_y":60,"max_z":344,"min_tile_x":23,"min_tile_y":51,"min_z":112},"placed_pieces":["begin_station","middle_station","end_station","flat_to_up_25",{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},"up_25_to_flat","flat_to_down_60","down_60","down_60","down_60_to_down_25","down_25","down_25_to_flat","flat_to_up_25","left_vertical_loop","down_25_to_flat","left_corkscrew_up","right_corkscrew_down","flat_to_up_25","up_25","up_25","up_25_to_flat","flat_to_left_bank","banked_left_turn_5","banked_left_turn_5","left_bank_to_flat","flat_to_down_25","down_25","down_25","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat","flat_to_left_bank","banked_left_turn_5","left_bank_to_flat","flat_to_right_bank","banked_right_turn_5","right_bank_to_flat","s_bend_right","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_fla… (2231 chars)

  9. Since ride length is the biggest scoring lever, I'll rebuild a longer layout keeping the same lift/loop/corkscrew opener, then add a southern section with a boosted half-loop, corkscrew, second vertical loop, and hills before returning north into the station.

  10. demolish
    {"demolished":0}
  11. new_ride
    {"dir":0,"ride_type":51,"x":60,"y":60}
    {"cursor":{"bank":0,"dir":0,"slope":0,"x":60,"y":60,"z":112},"ride_id":0}
  12. place_pieces
    {"pieces":["begin_station","middle_station","end_station","flat_to_up_25",{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},"up_25_to_flat","flat_to_down_60","down_60","down_60","down_60_to_down_25","down_25","down_25_to_flat","flat_to_up_25","left_vertical_loop","down_25_to_flat","left_corkscrew_up","right_corkscrew_down","flat_to_up_25","up_25","up_25","up_25_to_flat","flat_to_left_bank","banked_left_turn_5","left_bank_to_flat","flat_to_down_25","down_25","down_25","down_25_to_flat",{"speed":22,"t":"booster"},"flat_to_up_25","half_loop_up","right_corkscrew_down","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":25,"t":"booster"},"flat_to_up_25","right_vertical_loop","down_25_to_flat","s_bend_left","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat",{"speed":1… (1590 chars)
    {"circuit_closed":true,"cursor":{"bank":0,"dir":0,"slope":0,"x":60,"y":60,"z":112},"placed_this_call":88,"total_placed":88}

  13. Closed again. Testing.

  14. finish_and_test
    {"bounds":{"max_tile_x":63,"max_tile_y":60,"max_z":344,"min_tile_x":23,"min_tile_y":44,"min_z":112},"placed_pieces":["begin_station","middle_station","end_station","flat_to_up_25",{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},"up_25_to_flat","flat_to_down_60","down_60","down_60","down_60_to_down_25","down_25","down_25_to_flat","flat_to_up_25","left_vertical_loop","down_25_to_flat","left_corkscrew_up","right_corkscrew_down","flat_to_up_25","up_25","up_25","up_25_to_flat","flat_to_left_bank","banked_left_turn_5","left_bank_to_flat","flat_to_down_25","down_25","down_25","down_25_to_flat",{"speed":22,"t":"booster"},"flat_to_up_25","half_loop_up","right_corkscrew_down","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":25,"t":"booster"},"flat_to_up_25","right_vertical_loop","down_25_to_flat","s_bend_left","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25… (2500 chars)

  15. Locked in 6.66 with intensity maxed at 9.87—now I'll boost ride length by cutting the sharp s-bend and extending the east run to x≈88 south of the lake, then looping back on y=51 into the station.

  16. demolish
    {"demolished":0}
  17. new_ride
    {"dir":0,"ride_type":51,"x":60,"y":60}
    {"cursor":{"bank":0,"dir":0,"slope":0,"x":60,"y":60,"z":112},"ride_id":0}
  18. place_pieces
    {"pieces":["begin_station","middle_station","end_station","flat_to_up_25",{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},"up_25_to_flat","flat_to_down_60","down_60","down_60","down_60_to_down_25","down_25","down_25_to_flat","flat_to_up_25","left_vertical_loop","down_25_to_flat","left_corkscrew_up","right_corkscrew_down","flat_to_up_25","up_25","up_25","up_25_to_flat","flat_to_left_bank","banked_left_turn_5","left_bank_to_flat","flat_to_down_25","down_25","down_25","down_25_to_flat",{"speed":22,"t":"booster"},"flat_to_up_25","half_loop_up","right_corkscrew_down","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":25,"t":"booster"},"flat_to_up_25","right_vertical_loop","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat",{"speed":18,"t":"booster… (2251 chars)
    {"circuit_closed":true,"cursor":{"bank":0,"dir":0,"slope":0,"x":60,"y":60,"z":112},"placed_this_call":137,"total_placed":137}
  19. finish_and_test
    {"bounds":{"max_tile_x":90,"max_tile_y":60,"max_z":344,"min_tile_x":23,"min_tile_y":44,"min_z":112},"placed_pieces":["begin_station","middle_station","end_station","flat_to_up_25",{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},"up_25_to_flat","flat_to_down_60","down_60","down_60","down_60_to_down_25","down_25","down_25_to_flat","flat_to_up_25","left_vertical_loop","down_25_to_flat","left_corkscrew_up","right_corkscrew_down","flat_to_up_25","up_25","up_25","up_25_to_flat","flat_to_left_bank","banked_left_turn_5","left_bank_to_flat","flat_to_down_25","down_25","down_25","down_25_to_flat",{"speed":22,"t":"booster"},"flat_to_up_25","half_loop_up","right_corkscrew_down","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":25,"t":"booster"},"flat_to_up_25","right_vertical_loop","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat","fla… (3166 chars)

  20. Intensity spiked to 10.54 while excitement dropped to 5.2 due to too many drops and excessive turn speed. I'm rebuilding with a taller pre-turn hill for a slower banked turn, fewer hills, gentler boosters, and a shorter turnaround around x≈72.

  21. demolish
    {"demolished":0}

  22. Demolished. Starting the fourth build now: same opener, taller hill before the banked turn, fewer drops, shorter loop-back.

  23. new_ride
    {"dir":0,"ride_type":51,"x":60,"y":60}
    {"cursor":{"bank":0,"dir":0,"slope":0,"x":60,"y":60,"z":112},"ride_id":0}
  24. place_pieces
    {"pieces":["begin_station","middle_station","end_station","flat_to_up_25",{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},"up_25_to_flat","flat_to_down_60","down_60","down_60","down_60_to_down_25","down_25","down_25_to_flat","flat_to_up_25","left_vertical_loop","down_25_to_flat","left_corkscrew_up","right_corkscrew_down","flat_to_up_25","up_25","up_25","up_25","up_25","up_25_to_flat","flat_to_left_bank","banked_left_turn_5","left_bank_to_flat","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":22,"t":"booster"},"flat_to_up_25","half_loop_up","right_corkscrew_down","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":25,"t":"booster"},"flat_to_up_25","right_vertical_loop","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_25","down_25","down_… (1815 chars)
    {"circuit_closed":false,"cursor":{"bank":0,"dir":0,"slope":0,"x":61,"y":60,"z":112},"placed_this_call":114,"total_placed":114}

  25. Circuit missed by one tile in x (my east run was one tile long). Undoing the last 14 pieces back to the turnaround, then re-laying the west leg one tile shorter.

  26. undo_piece
    {"cursor":{"bank":2,"dir":0,"slope":0,"x":62,"y":60,"z":112},"pieces_placed":113,"removed":"left_bank_to_flat"}
  27. undo_piece
    {"cursor":{"bank":2,"dir":1,"slope":0,"x":64,"y":59,"z":112},"pieces_placed":112,"removed":"banked_left_turn_3"}
  28. undo_piece
    {"cursor":{"bank":0,"dir":1,"slope":0,"x":64,"y":58,"z":112},"pieces_placed":111,"removed":"flat_to_left_bank"}
  29. undo_piece
    {"cursor":{"bank":0,"dir":1,"slope":0,"x":64,"y":57,"z":112},"pieces_placed":110,"removed":"flat"}
  30. undo_piece
    {"cursor":{"bank":0,"dir":1,"slope":0,"x":64,"y":56,"z":112},"pieces_placed":109,"removed":"flat"}
  31. undo_piece
    {"cursor":{"bank":0,"dir":1,"slope":0,"x":64,"y":55,"z":112},"pieces_placed":108,"removed":"flat"}
  32. undo_piece
    {"cursor":{"bank":0,"dir":1,"slope":0,"x":64,"y":54,"z":112},"pieces_placed":107,"removed":"flat"}
  33. undo_piece
    {"cursor":{"bank":0,"dir":1,"slope":0,"x":64,"y":53,"z":112},"pieces_placed":106,"removed":"flat"}
  34. undo_piece
    {"cursor":{"bank":4,"dir":1,"slope":0,"x":64,"y":52,"z":112},"pieces_placed":105,"removed":"right_bank_to_flat"}
  35. undo_piece
    {"cursor":{"bank":4,"dir":0,"slope":0,"x":66,"y":49,"z":112},"pieces_placed":104,"removed":"banked_right_turn_5"}
  36. undo_piece
    {"cursor":{"bank":0,"dir":0,"slope":0,"x":67,"y":49,"z":112},"pieces_placed":103,"removed":"flat_to_right_bank"}
  37. undo_piece
    {"cursor":{"bank":0,"dir":0,"slope":0,"x":68,"y":49,"z":112},"pieces_placed":102,"removed":"flat"}
  38. undo_piece
    {"cursor":{"bank":0,"dir":0,"slope":0,"x":69,"y":49,"z":112},"pieces_placed":101,"removed":"flat"}
  39. undo_piece
    {"cursor":{"bank":0,"dir":0,"slope":0,"x":70,"y":49,"z":112},"pieces_placed":100,"removed":"flat"}

  40. Cursor is at (70,49) heading west. Placing the corrected west leg and closing turns.

  41. place_pieces
    {"pieces":["flat","flat","flat","flat","flat_to_right_bank","banked_right_turn_5","right_bank_to_flat","flat","flat","flat","flat","flat","flat_to_left_bank","banked_left_turn_3","left_bank_to_flat"]}
    {"circuit_closed":true,"cursor":{"bank":0,"dir":0,"slope":0,"x":60,"y":60,"z":112},"placed_this_call":15,"total_placed":115}

  42. Closed. Testing this build.

  43. finish_and_test
    {"bounds":{"max_tile_x":75,"max_tile_y":60,"max_z":344,"min_tile_x":21,"min_tile_y":42,"min_z":112},"placed_pieces":["begin_station","middle_station","end_station","flat_to_up_25",{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},"up_25_to_flat","flat_to_down_60","down_60","down_60","down_60_to_down_25","down_25","down_25_to_flat","flat_to_up_25","left_vertical_loop","down_25_to_flat","left_corkscrew_up","right_corkscrew_down","flat_to_up_25","up_25","up_25","up_25","up_25","up_25_to_flat","flat_to_left_bank","banked_left_turn_5","left_bank_to_flat","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":22,"t":"booster"},"flat_to_up_25","half_loop_up","right_corkscrew_down","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":25,"t":"booster"},"flat_to_up_25","right_vertical_loop","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_… (2735 chars)

  44. Banked 6.87 with intensity 9.93, just under the ceiling. Confirming the banked score.

  45. best_result
    {"bounds":{"max_tile_x":75,"max_tile_y":60,"max_z":344,"min_tile_x":21,"min_tile_y":42,"min_z":112},"placed_pieces":["begin_station","middle_station","end_station","flat_to_up_25",{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},{"chain":true,"t":"up_25"},"up_25_to_flat","flat_to_down_60","down_60","down_60","down_60_to_down_25","down_25","down_25_to_flat","flat_to_up_25","left_vertical_loop","down_25_to_flat","left_corkscrew_up","right_corkscrew_down","flat_to_up_25","up_25","up_25","up_25","up_25","up_25_to_flat","flat_to_left_bank","banked_left_turn_5","left_bank_to_flat","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":22,"t":"booster"},"flat_to_up_25","half_loop_up","right_corkscrew_down","flat_to_down_25","down_25","down_25","down_25","down_25","down_25_to_flat",{"speed":25,"t":"booster"},"flat_to_up_25","right_vertical_loop","down_25_to_flat","flat_to_up_25","up_25","up_25_to_flat","flat_to_down_… (2735 chars)

  46. Best banked result this round is confirmed. Four builds were tested: | Build | Pieces | Length | Inversions | Intensity | Excitement | |---|---|---|---|---|---| | 1: loop + corkscrews, short return | 71 | 467 | 2 | 8.63 | 6.09 | | 2: added half loop + second loop | 88 | 580 | 4 | 9.87 | 6.66 | | 3: long hill run to x=90 | 137 | 818 | 4 | 10.54 | 5.20 | | 4: fewer drops, slower banked turn | 115 | 714 | 4 | 9.93 | **6.87** | Build 3 showed the ceiling clearly: extra hills pushed intensity past 10 and excitement collapsed. Build 4 kept the four inversions, cut the drop count back to ten, and used flats and brakes on the loop-back leg to stay just under the limit. Similarity to the stock library is 0.39, so no penalty applied. Nothing was named or coloured. Best coaster: 115-piece twister with a 12-tile lift into a 60° drop, vertical loop, corkscrew pair, boosted half loop with corkscrew, and a second vertical loop, closing via banked turns south of the lake. Excitement 6.87, intensity 9.93, nausea 5.76.

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