i figured that attempting it with the polar star was a fool's errand, but i did do it with the machine gun!
anyway, here's a thing
Knytt Stories
I think a lot of people were put out by "Knytt" coming out after the uniquely Scandinavian bounce-a-thon that was "Within A Deep Forest", feeling it was kind of dull and empty. Personally I like Knytt, but I can see where the complaints are coming from (although it's not like WaDF didn't suffer from it, too). Knytt Stories keeps the minimalist mood from Knytt but gives the player more to do, in the form of Metroid-style power-ups. It also has an editor and a bunch of great add-ons, so once you've beaten the main game, "The Machine", the running around doesn't have to end. The add-on worlds can also be found on Nifflas' site: I recommend pretty much everything else Nifflas has made for the game ("A Strange Dream", "Gustav's Daughter" and "An Underwater Adventure", in particular), and "Afar" (which is a nightmare on hard mode, by the way). There aren't that many great ones, yet...
Poyo
Kind of an old standard, I've talked about this game before but there's no harm in going over it again as it's not real well-known. You are Poyo, a little purple dude with the ability to "warp", a short-term form of teleportation. You wish to escape the world you live in, but to do so you must travel through 50 levels to meet with the Ruler before you can use his interdimensional hatch. Great fun, maybe a bit easy though. I personally didn't think much of the music supplied with the game, so if you like you can download my replacements
here (unzip and overwrite into the game's music directory)
Plasma Warrior
A short Metroid clone, which takes what Nintendo tried (and failed, in my opinion) to do with musical/graphical atmospherics in the original Metroid, and does them much better. You control a scouting robot who must find data on the sudden disappearance of the entire personnel of an extraterrestrial excursion. It's great, the game feels weirdly foreboding, but as I said, it's very short; I beat it inside of an hour.
Paroxysm
Found this on the same site as Plasma Warrior. You are in an ultraviolent deathtrap of a dungeon and have to escape it. Kind of easy to blow through, although there are multiple paths to choose. Lots of horrible, torturous fun!
also, if we're talking flash games, here's some great ones:
Grow Series (there are like a billion of these)
Pieces (a lot like knytt stories, pretty cool)
Open Doors (really goddamn hard, i got to level 12)
Shift (actually, shift 2 is better, but play both)
Also, I feel kind of bad for giving Cave Story an honorary mention but not Lyle in Cube Sector or WaDF, even if everyone does know about them. So:
Lyle in Cube Sector (THE FUKKEN SHIT)
Within a Deep Forest (i should note that all these nifflas games would not be as good without sara sandberg's little characters populating the scenery, so let's hear it for her)
and while i'm at it:
Aquaria (not freeware, but the demo is free, ~2 hours long and totally worth playing. it appeals to the part of me that likes girly fantasy crap, like those silly gothic metal bands)
i'll add more games to this thread as and when i feel like it. advertising is fun