Flash Games I've Kinda Liked 3

Crush the Castle 1 - Destroy enemy castles with carefully placed catapult shots. Physics shooter.

Crush the Castle 2 - More of the same, new weapons, etc.

The Deeplight Expedition - Search the caverns for tablets telling of the labyrinth's creation and magical runestones ultimately granting access to the Deeplight Stone. Fun and cute little exploration focused platformer.

e7 - You are a probe landed on a bizarre planet, apparently coated with a thick layer of animate organism. Find and destroy a bomb aimed at the Earth fighting alien drones and using the planet's weird properties along the way. Simple but neat concept and graphics, nice design.

Little Loki - A leet little imp trying to escape hell. Neat sort of silhouetted design.

Halo 2600 - Halo as designed for the Atari 2600. Can't say I loved play, but did enjoy the retro style design.

The Fountain - Novel platformer where you start out as a single pixel only able to jump a small distance but grow in size and capability as you recover missing pieces of yourself. Maybe some sort of commentary on something.

Raiden X - Top scrolling air/space ship shooter game, modeled on Raiden I & II with a nice retro feel to it. If you have a hankering for top scrolling 2D flight/shooter games then you would be hard pressed to do better than this for free.

Starmageddon - Yet another top scrolling space ship shooter game. Ok, but not as good as Raiden X.

Nostradamus - As far as I can tell the name has little to do with the contents of the game. Another nice retro top scrolling air/space ship shooter game.

Outzone - Single character retro-shooter. Essentially futuristic commando vs. alien invasion. Vaguely like a top scrolling version of Contra.

That's all that come to mind at the moment.