I'm looking for some decent racing games that I can play with my dad on our iPads. Some of the recommendations I've found online have dozens of in-app purchases and he's not going to be into that (and neither will I). I'm looking for something that can be bought up front or unlocked for a one-time fee (like Horizon Chase, which is unfortunately not multiplayer). By racing I'm referring to cars, motorbikes, etc. No 32-bit apps please; not a worth investing in something I won't be able to use in three months.