Btooom!, Dorei-ku The Animation Recommendations
-Both anime has Crazy/obsessed people.
-Both anime has games and dueling in them.
-In both anime loser gets punished .
Both stories are about a male and a female MC who start to play willingly or not some very dangerous games that can cost them their lives.The male MCs are pretty clever and used in those games, so they mostly dominate or outsmart their oponents. The side character and villains are some obsessed or crazy in the head people.