If you like 2D physics-based racing, Trials Frontier is one of the best on iOS.
The tracks are filled with obstacles and jumps, letting you get big air while you race to the finish line.
After a few tutorial races you'll get to the Village. Here you can build new bikes, upgrade your current ones, and get quests to explore the world.
When you enter the saloon, you'll be met by some of the game's many strange characters. Each have quests for you that include finding special items, pulling off stunts in races, and more.
In this slide you can see some of the many tracks available to race. But this is only a fraction of the entire map. In other words there is plenty to explore in this game.
Part of the fun in this game are the stunt challenges given to you by the NPCs in the saloon. Some require things such as completing five backflips before the end of a race.
As you progress you'll find blueprint pieces that will eventually let you build new bikes. But you can also upgrade each bike with parts you earn as you race.