The original Rollercoaster Tycoon 3 cheats also work with the expansion:
John D Rockefeller - Add $10,000 Mouse - Guests stare at the gound Atari - All guests laugh and cheer Frontier - Rides/Coasters never break down Guido Fawkes - Advanced fireworks editor Sam Denney - Peeps ride all coasters Jon Roach - Peeps ride all non-coaster rides John Wardley - Removes height restrictions on coasters James Hunt - Buggy rides through the park Shifty - Guests dance ATITech - Speed up
While playing, click on a peep in your park. Click the General Information button (has an "i" on it). Click the peep's name, then delete or backspace over it. Enter the cheat code as the name, then press Enter.
Codes Effects Alistair Lindsay - SoundWarp M Brookes - Underground SI Mornington Crescent - Allow Path Walls Rick Griffiths - Tunnel Shark