Antigraviator can be pretty challenging for those not familiar with anti-gravity racing games such as F-Zero.  There aren't a lot of upgrades for your vehicle and requiring credits to attempt later leagues can be a bit detrimental as you might have to replay the first league multiple times just to grind credits.  The traps are also not really my cup of tea and I could do without those personally.  Beyond that though, Antigraviator is a solid game, but it's not for everyone.