Also, a game doesn't have to be revolutionary, complex, or even particularly deep to succeed. In fact, the simpler the game is, the better, when you are a small developer. See Tetris,
www.popcap.com, Commander Keen, etc.
These are not particularly advanced games. They just used one good idea and made a *reasonably* good model of that idea. These simple games will be around much longer than the next incarnation of some 3D shooting fiasco.
BTW: It is also possible to mail yourself a cd-rom image of your work in an envelope with the stamp over the seal, thus providing your work with a valid time/date stamp from the post office, but this will NOT be sufficient a priori to sue for damages. The most you could accomplish from this would be a cease-and-desist order.
Also, in the case of serial work and compilations, if you are able to convince the copyright issuers that your work is necessarily part of a package (as in an album, a magazine volume, etc.) you can have all of the series copyrighted with only one payment. Perhaps, if you are going to copyright a bunch of small games, it would be wise to first release them as Joey's Value Pack o' Whole Crapload o' Games or something.