VVVVVV is a game created and developed by Terry Cavanagh that was released in early 2010. It mixes awesome platforming elements with those weird gravity-involving games.
At first glance this game looks like any old platformer game with elements that involve gravity, and to some people, it might just be that. But I, personally, had a lot of fun with this game. It's like a mixture between Jumper (without the double-jumps and such) and that weird gravity engine that was released with Slayer64's "everything pack", or whatever it was.
You are a man. Well, maybe not a man. A humanoid at least. You are a humanoid who is the captain of a spaceship. This ship explores the galaxy for one reason or another. So, anyway, one day something strange shows up on the ship's radar, and suddenly it crashes for no discernible reason. You, the captain, are apparently the only survivor. You set out to find out what happened and, if possible, rescue any other live crew members.
In this adventure, instead of jumping, you can flip the personal gravity of the captain by 180 degrees. In other words, the ceiling becomes floor and the floor becomes ceiling. There are strange things with C's on them all over the game, and these are checkpoints. If you die anywhere in the game (which will happen a lot), you will be teleported to the last checkpoint you touched.
There are many secrets in VVVVVV, and also alternate game modes. Though the game isn't too long, it'll occupy your time for a long time, and has a lot of replay value. The soundtrack (composed by SoulEye) is very catchy and keeps you happy throughout the whole game.
Unfortunately, this game is not freeware. It costs $5 to buy/download, but then after that, you can give the installation application to anyone you like, as long as it's privately (and not for any money). Unfortunately, the soundtrack costs money too. $4, I believe.
-Fun, addictive gameplay
-Checkpoints everywhere, so if you die, it won't be a very big deal
-Lots of fun platformer elements
-Awesome, addictive music (if music can be addictive)
-Tons of secrets and unlockables
-It's not freeware
-Could be longer
-Extremely hard in a couple places
I'd say, in my opinion, this game is well worth the money. It's jam-packed with as much as a little game could handle, and it's super fun. The addictive gameplay ups the replay value by a ton.
Play 2-Level Demo at Kongregate
Buy the Full Game ($5)
Buy Official Soundtrack ($4)