Rombo Rush is a Rombo spin-off with fast paced action FPS gameplay and retro pixel art where you have to fight the hordes of monsters coming at you in waves. The game features a fast 3D raycasting engine, gothic fantasy levels and a HUGE horde of enemies to fight. It used to be available through the MochiAds network before it shut down.
You can play Rombo Rush by clicking here. Use arrow keys or WASD to move, Z or Ctrl to shoot (or open a hidden door), Enter or Shift to turn around 180 degrees, Q/E to strafe left and right and Esc to pause the game. The controls are reconfigurable from the Options screen.
When you start a new game, you start in a randomly selected map. To finish the map you have to kill as many monsters as mentioned at the top-right corner of the screen (xx MORE). The game starts with weak monsters but after a few turns you will encounter harder monster types.