I need to look through the games already posted again, because there are so many :O But, I'm very picky about which games I recommend since there are so many out there... So many games... so little time

Well here are the games that I recommend. (All for PC)
I believe each of these games have exceptional qualities.
tier 1 means pretty much perfect.
tier 2 is still awesome.
tier 3 still has outstanding qualities but maybe lacking in another area.
*D means demo available
*F means freeware
*C means only commercial
tier 1 games :
=Aquaria *D
http://uk.youtube.com/watch?v=YqY9mDOw-UI[It's Aquaria silly! (I got a couple people to buy it too

)]
http://www.bit-blot.com/aquaria/index.html=Cave Story *F
http://uk.youtube.com/watch?v=7dr6-NKqVwk[who hasn't heard of this one!? Action!]
http://www.cavestory.org/=Iji *F
http://uk.youtube.com/watch?v=33mxD4FjD3w[this is a newly released action freeware game... very nice.]
http://www.remar.se/daniel/iji.phptier 2 games :
=Darwinia *D
http://uk.youtube.com/watch?v=cQruXxfeGXA[strategy game... not freeware, but really interesting]
http://www.introversion.co.uk/darwinia/=Bionic Commando : Rearmed *C
http://uk.youtube.com/watch?v=kcutOllbECk[if you loved the original Bionic Command move this to tier 1]
http://www.bioniccommando.com/=Melty Blood Act Cadenza ver. B *D
http://uk.youtube.com/watch?v=Y-7u-rwTNkY[Best fighting game I've played in a long time... can be multiplayer]
http://mirrormoon.org/news/2008/10/melty_blood_act_cadenza_trial_english_v1_0_released=Starsiege : Tribes *F
http://uk.youtube.com/watch?v=LvdkzioSzVc[old free multiplayer FPS game... best of its kind, as far as I know :O Can have a steep learning curve...]
http://www.fileplanet.com/140246/140000/fileinfo/Starsiege:-Tribes-Full-Game?r=5=Crescent Pale Mist *C
http://uk.youtube.com/watch?v=Pep3oVlAafE[if it were in english, it'd be tier 1. Action game.]
http://classic-shikoukairo.jpn.org/=Ether Vapor *D
http://uk.youtube.com/watch?v=g2r7-JS4Wkc[Awesome shooter... again not in english. It seems to be really fun.]
http://edelweiss.skr.jp/works/ethervapor/index.html=Trouble Witches *D
http://uk.youtube.com/watch?v=sKJst6ylTGM[if it was in english it could be a tier 1 cute shooting game :O]
http://trouble_witches.mails.ne.jp/tier 3 games :
=Another World (Out of this World) *D
http://uk.youtube.com/watch?v=yeS-x7e4YRw[Toooo short! Totally awesome. Action game.]
http://www.anotherworld.fr/anotherworld_uk/index.htm=Within a Deep Forest *F
http://uk.youtube.com/watch?v=y6QX5DmiOTg[I liked this a lottt more than Knytt]
http://nifflas.ni2.se/index.php?main=04Within_a_Deep_Forest=Cloudphobia *F
http://uk.youtube.com/watch?v=qz0zO06yHHY[Work in progress... but the most interesting/refined freeware scrolling shooter game I've played]
http://www.dwahan.net/uki/=the white chamber *F
http://uk.youtube.com/watch?v=zk7WPlPNEns[freeware horror sci-fi adventure game... more of a scary short story than anything else]
http://www.studiotrophis.com/site/projects/thewhitechamber=Sixty Five Million and One BC *D
http://uk.youtube.com/watch?v=3XtYfU-Gh4E[humours dino action

]
http://www.65millionand1bc.com/index.php=Utawarerumono Battle *C
http://uk.youtube.com/watch?v=oHUXVyNIDZY[move this arcade action game to tier 2 if you've played Utawarerumono]
http://leaf.aquaplus.co.jp/product/aru/I vouch for all these games to be exceptional in some way, descriptions and footage is within the youtube link~
I kinda want to put images up to make it easier and descriptions but whew I'm tired out!