SuperSlots allows American players, but they leave a bit of a loophole in their terms and conditions, saying that players are responsible for making sure that online gambling is legal in their jurisdiction. They don’t allow residents of Canada or The Netherlands, though. Of course, players have to be at least 18.
For bonuses, it feels like SuperSlots is really a jackpot. They offer 150% bonus, up to $150 for first deposits. They also offer crazy amounts of comp points, plus deposit bonuses on Mondays, Wednesdays, and Fridays. There are also all kinds of random bonuses and coupons available, plus there’s a VIP club that increases all the bonuses and the rate at which comp points are accumulated.