Hilly.io is one of those online 2 player games. .io series always create enjoyable multiplayer games for you. Hilly is a race among balls on hilly tracks. Holding LMB set your speed in this race. The point is that deciding when to get slow not to lose speed on hills. If you crash toward a hill, your speed will be zero. But if you get slow before the crash, you can climb it faster. This is why good racers always know when to get slow in races!
How to Play?