A hundred and ninety-nine games from Grandmaster David Bronstein, all starting with P-K4 P-K4 (or, in algebraic notation: e4 e5). These then are all "open" games, and well over half are Ruy Lopez.
The appeal of "200 Open Games" (the last one in the book is effectively a joke) is not the range of openings, nor even the significance of most of the included games, but rather the insight into the mind of probably one of the best (and certainly one of the most creative) chess players to come out of the former Soviet Union. GM Bronstein provides honest, often funny, comments about what was going through his head when he played critical moves in each of these games. He also shares nice reminiscences of opponents through the 40s, 50s, and 60s.
My favorite? Probably his comments in 1961 USSR Chamionship win against Alexander Cherepkov:
"How many delightful combinations I have ruined in my many years of tournament practice only because of the fact that I noticed a counter-combination for my opponent, a combination which my opponent was not even thinking about and (which was more often the case) which just was not there at all, either on the board, or in his thoughts."
Admirably translated by Philip J. Booth, who succeeds at retaining Bronstein's, dare I say, naughty wit. This was originally a Batsford title (London, 1973) and is now published here by Dover, who offer many excellent chess books, reasonably priced and well made.
If, after enjoying this book, you find yourself wanting more of this opening (especially for Black), check out Play 1e4 e5
Play 1e4 e5: A Complete Repertoire for Black in the Open Games (Everyman Chess)