I think those are well know lite that widely use right now that i can see in any website or gamlbing sites are dogecoin ethereum litecoin clams.. in crypto games.. but i didnt know the other site that accept altcoin..
Some casinos are accepting altcoins on top of Bitcoin. FortuneJack is accepting: Dash, NMC, CLAM, DOGE, RDD, PPC, NVC and of course Litecoin.
DirectBet - wide known sportsbook is accepting: BTC, Litecoin, Dogecoin, Dash & Ether there are more, but I suspect altcoin are not used that much at all.