Hot Wheels presents a crappy looking halfpipe skateboarding game that allows you to gain big air quite easily. There are multiple game modes, coolest is the match play in which you’ll play against a computer controlled opponent and try to gain more points when it’s your turn.
Press and hold the spacebar to gain momentum in the halfpipe, release the spacebar when you’ve reached the top to jump. Use the arrow keys to perform tricks, and finish them before you land.
Source
http://www.playskateboardgames.com/play-free-hot-wheels-half-pipe-challenge-game/