Now, I might be a bit dated with my suggestions, but I swear they're fun if you can get a few friends together to play them~
FPS:
Pirates, Vikings, and Knights II (fps with, you guessed it, pirates viking and knights! Each 'race' has a couple classes you can play and each race has a special class. objectives, deathmatch, and even arena matches are featured!)
Modular Combat (based on half-life. Multiple servers/mods for said servers. Many ways to play. Accounts are server specific so it saves stats per server for you!)
Solo RPGs:
Princess Remedy in a World of Hurt (easy bullet hell type)
Heroine's Quest: The Herald of Ragnarok (Actually pretty hard. Text is your friend here)
And, what list would be complete without some MMO suggestions:
Fishing Planet (An arcade sim of fishing. Rpg elements, actual in depth settings and equipment to use. Can be played with friends)
World of Fishing (total arcade version of driving a boat in an ocean and fishing with friends)
Riders of Icarus (MMORPG about fighthing and taming just about any creature in the game, allowing you to ride them!)
Tree of Savior (MMORPG with a unique viewing angle. Tons of people play and there are LOTS of ways to play it with it's special class trees!)