Rule 1: You have to build a junior coaster in your park. It must use one of the junior coaster vehicle types from RCT2 or one of its official expansions, but not the rocket cars. You are not allowed to use steep drops.
EDIT: You are also allowed to use the mine train coaster trains.
EDIT 2: The coaster must be a continuous circuit.
Rule 2: If you look at the stats of your junior coaster, the stat for highest drop may not be higher than 7 meters, and the ride length is not allowed to be more than 400 meters. If you use imperial units, simply set the game to meters in the settings and then check your stats.
Rule 3: Other than the junior coaster, you are not allowed to have any opened rides. Shops and stalls that are opened are allowed.
Rule 4: You are allowed to have as many other rides as you want, as long as they are closed or in test mode, and don't carry any guests.
Rule 5: The maximum map size is 18 x 18 tiles! This may sound arbitrary, but this size would fit all the junior coasters that I have built so far, with 1 or more tiles open on both sides.
Rule 6: You are not allowed to use any custom scenery, custom rides or other custom objects in your park, except for a custom palette!
Rule 7: The deadline will be Friday the 5th of June 2020, at 19:00 CEST.
Rule 8: Have fun!

Noobiestnoob