If games weren't challenging, we wouldn't bother with them, right? Games create a set of rules that cause certain actions to be difficult, then you, the player, must try to perform those actions. It's a narrow definition, to be sure, but challenge on any level is something that sits at the core of gaming. Each of the games below throws challenges at you in a different way, whether it's via enemies, puzzles, restrictive physics, or a combination of all three. Sometimes you have to form a strategy, but sometimes it's about fighting with the game itself to make it all work. Either way, it's fun.

Shards (Windows, 17.4MB, free) - An excellent experimental platform game where you move through levels by gaining momentum via rolling and jumping. It's much more challenging than that description sounds, as sometimes the simplest-looking jump requires you to backtrack and gain considerable speed before attempting it. The creator, Jeroen Stout (Bodilies), considers this a prototype, so don't be surprised if you encounter a few rough edges here and there.

Hydorah (Windows, 18MB, teaser) - A free "demo" for a work-in-progress shmup, Hydorah is old-school in every way. Fight against hordes of aliens through a series of short, intense levels, using primary and secondary weapons you can unlock and select as you progress. There's just one difficulty level, and it's cranked up so high you'll have a rough time even in the first stage. When it comes to retro challenge, this game does not fool around. It's so serious, it warns you before you even get to the title screen. Yeah. If this were an arcade machine, you might as well hand over your roll of quarters up front. Created by the author of 8-bit Killer.

Battle of Tiles (Windows, 18.5MB, demo) - A casual war strategy game at its core (but with liberal sprinklings of RPG elements), Battle of Tiles pushes simplicity to the forefront and delivers a captivating turn-based tactics experience that only gets better as you play. You control a party of knights, archers, mages and priests, each represented by a single tile. Advance through wave after wave of enemy tiles while you arrange your fighters in the best possible formation. Level-up units, swap them with weaker soldiers, bribe enemy units to join your side, and amass a glorious army that can be as many as 70 strong. Bosses are a particular high point in the game, requiring a delightful mix of puzzle solving and strategizing to conquer. It's impressive that a game manages to take tactical combat and strip it to its essentials without losing the fun, but Battle of Tiles has done it well.

Note: All games have been confirmed to run under Windows Vista and are virus-free. Mac users should try Boot Camp, Parallels, or CrossOver Games to play Windows titles, Linux users can use Wine. If you know of a great game we should feature, use the Submit link above to send it in!