BrikWars challenges you to take all the random Lego, Playskool, and other construction/little plastic toys you have around, and fight battles with them -- with a clever set of rules that encompasses the basic tropes of the hardcore miniatures game, but with an unusual "rules are made to be broken" slant.
For me, the greatest barrier to miniatures gaming has always been that painting figures takes forever, and I have no interest in it; playing the game might be fun, but the craft-hobbyist aspect of assembling, painting, and fielding your army leaves me utterly cold.
And, of course, I don't have any great desire to make Games Workshop rich(er than they already are, anyway), nor to spend hours arguing with pedantic autodidacts about the right button colors on Napoleonic uniforms.
But I can readily see the appeal of BrikWars, particularly if you have an extensive childhood collection of Lego sets -- beyond the basic bricks, I mean, vehicles and dinosaurs and construction equipment and what not. BrikWars has a pretty good set of rules for assigning basic combat stats to just about anything, based on size, number of brick nipples, and the like; and the result is sort of the trans-dimensional, chaotic game that would make devotees of "generic" RPG systems shudder: ninjas, WWII marines, and Jedi Knights, all in the same battle. Why not?
Naturally, if you're trying to create a game that can literally encompass the universe (of little plastic toys, at any rate), there are two directions you can go: Toward hypercomplexity, so you have a rule to handle every conceivable situation -- or to an open-ended system that says "Here's the basics, improvise to your hearts content." Rayhawk's original game took the latter path, but miniatures gamers are the most fanatic of rules Nazis; I've seen passionate arguments over board and roleplaying games, but whole wars have been fought (or, actually, not fought) over minor rules disputes by miniatures gamers. His 2001 edition tried the second approach, with extroardinarily complex rules, which some branded as unplayable; but the modern edition returns to the core, and correct path.
That is, if you want special firebreathing rules for your plastic dragon, you'll need to negotiate them with the other players. But the core rules are an excellent structure on which to build a battle.
Morever -- they're actually well written, and more, fun to read; many non-commercial rules sets make you wonder whether their authors graduated high school, and even professionally produced rules are sometimes poorly written, and more often, dreadfully dull. Rayhawk writes with wit and spirit.