Mmm.  There really isn't a great way to start off a roundup of open-source and freeware games.  We should just be able to say that: "Hey!  Over here!  Free games!  Free, fun games for you to play!  Come play them!"  But that would be a dull and uninteresting way to start a feature article about free games.  So with that out of the picture and all, let's just spare the verbal exchange and get right into the killer titles. Trust us, this week's batch of titles is so fun, you won't want to read introductions in place of what you're about to start playing.

Omar's Orthogonal Oyster Outing

What is it:  Remember Omar's Oyster Outing?  We tossed you this game some time ago, so it's ok if you've forgotten about this killer... zombie-killing... title.  Allow us to get you up to speed.  In Omar's Orthogonal Oyster Outing, you play the role of Omar -- the sole human alive in a city full of zombies.  Your goal?  Survive.  Survive and escape.  While you were constrained to a paltry two dimensions in the original title, this remake gives your futile quest for life a three-dimensional upgrade.  Don't expect to scale walls and do other crazy Spiderman stuff.  But at least now, when the zombies come to overtake your fear-drenched self, it'll look a lot prettier.

Download it here!

Tag: The Power of Paint

What is it: Fresh out of Digipen, this puzzle-based first-person shooter drops you into a monotone world.  To progress through the levels, you have to use the powers of your paint-gun -- kind of like a Super Soaker that you can fill with various colors of paint -- to interact with the black-and-white levels in various ways.  The gameplay reminds us of Portal, were the blue-and-orange linked gateways replaced with gooey blobs of color.  It's an ingenious game that will have you debating whether you should actually run through the levels to finish them... or just to color them.

Download it here!

Ping Pong

What is it: This is not your average Atari ping pong title.  It sure looks like one.  But there's actually a good deal of strategy built into this game, styled after the best of the 8-bit  universe.  Depending on the various keys you press while shooting, you can actually control the style of shot you're hitting against computer (or real-life) players.  With but one file to run, this game makes for a great, portable time-waster--just slap it on a USB key and run it whenever you have the craving for some hot, pixilated ping-pong action.

Download it here!

Gusanos

What is it: Real-time Worms?  2D Quake?  However you want to describe it, the action-packed atmosphere of this side-scrolling shooter is as addictive as it is destructive.  It can be a bit tricky to run for those with huge monitors, but the payoff is worth it.  Run around an assortment of levels, blasting bots (or humans) with all sorts of Quake-style weaponry.  If you liked Gang Garrison, you'll find similar enjoyment with Gusanos.

Download it here!

Blocksum

What is it: This game will drive you nuts.  No, seriously.  It's a puzzle game that uses small, numbered blocks to fill rows.  Your goal?  Combine the blocks together to create a large mass whose number then equals that of the sum of the smaller blocks. When you do that, the mass starts blinking.  If it touches an identically numbered block or mass, that chunk starts blinking too.  This isn't a flash graphical reminder; it's a countdown.  The connected masses eventually explode, clearing the way for more numbered blocks, more masses, and more fun!

Download it here!