Robombs is a free Java based Bomberman style multiplayer game that's set in a 3D environment. It's free to play and you'll usually find other players across to the net to play against.
You can choose to play on a single player game against the CPU but it's far more fun to choose someone online. There are 9 levels that see you navigate a maze surrounded by boxes. Your opponent starts on the other side of the grid and their aim is to blow away the boxes collect as many skulls and other bonuses as possible before your opponent reaches and eliminates you. The way you clear the boxes and empty them of their contents is to plant the bombs next to them but then you've got to run for it and avoid being blown up yourself.
If there's any real drawback, it's that the controls are not properly explained from the start although they are on the developer's site. You rotate your view with the mouse and you move with WASD, the cursor keys or the numerical keypad. The mouse wheel also zooms in and out. Clicking left activates a water pistol that allows you to defuse bombs and clicking right allows you to plant a bomb. The problem is that the bombs give you way too much time to escape so Robombs is not as challenging as it could be. The other slightly annoying thing is that it's written in Java so you have to wait for that to initialize before you can get going.
If you like Bomberman style games, maze challenges and lots of explosions, then you may find Robombs interesting, if only for a while.