UBERMOSH is a simple and very difficult arcade game similar to Robotron: 2084. As a smooth twin-skick shooter, it plays equally well with a mouse and keyboard or gamepad. (I usually find a mouse better for precision aiming and the gamepad for twitchy movement. I think the gamepad is slightly better for this game.) Enemies (technically competitors) stream in from the edges of the playfield attempting to kill you. Fortunately, you are armed with a gun and a sword. The sword is particularly useful as it serves both close combat and deflecting bullets. The game offers several player classes, including an arguably overpowered sword-only Kensai which can use no guns, but gets 6 lives. Mastering the sword is the key to the game, so it's a good class to start with.
You will die—constantly. Winning isn't possible, but there are steam achievements and high scores. (I gather a round ends after 90 seconds, which could be considered a win state if you make it.) It's really a classic arcade style designed to eat quarters. Fortunately, restarting is free (and quick). The idea is to keep learning from mistakes and improving your skill. It can feel a little bit unfair since the viewport is small compared to field of play. Enemies and projectiles come from all directions, but it would be nice to see more so that you can plan your moves. Still, most hits can be avoided with skill.
Also, quite listenable music.