Like ATLust, BARE has its own website and community to offer help with any questions you might have so I'll keep this short. BARE is a card style fighting game that can be played anywhere in SecondLife where you can rez objects. Your goal is to defeat your opponent by lowering their health bar to zero. To make this easier you can destroy their "armour/clothing" by targeting specific body parts. Once a clothing part is "destroyed", attacks on that part of the body do more damage. Plus you can set up BARE to interact with your avatar, so as you lose armour in the game, your avatar loses clothing. At the end of the game, the winner gets to "punish" the loser through a selection of sexy interactions.
The game itself is free, but via the JasX website you can purchase cosmetic packs that add effects to your attacks and punishments.
As an extra bonus, there are plugins you can get to connect BARE to Project Arousal.You can get a copy of BARE from any BARE kiosk. If you search for BARE arenas you should find one pretty easily, or click the image below for a link to the BARE kiosk at Nakasuni.