Players are tasked with separating various animal species, referred to as "critters" into their own pens by building a fence between them. Each critter species has their own abilities or quarks, such as lions who roar and stun the player or rabbits that can enter underground burrows and reappear in another part of the map. Critter Round-Up has influences from the arcade classic QIX. There are multiple game modes and mini-games:
Adventure - 1 or 2 players travel through 5 different environments in 50 levels.
Co-Op Challenge - similar to Adventure mode, but with specially designed levels that support up to 4 players across 20 levels.
Marathon - randomly selected level size and critter types for 1 to 4 players.
There are also four competitive mini-games that support 2 to 4 players:
Snowball Soccer - get the snowball into your goal with a little help from some giraffes.
Predator Rampage - try to avoid the running critters for as long as you can. Critters keep getting added to the level as well as speed up over time. The last player standing wins.
Fence Attack: clearly inspired by the light cycles of Tron, try to get the other players to run into the fences that everyone is building.
Chicken Catch - there's dozens of different colored chickens running loose, each worth a different amount of points. The player with the highest score wins.