I'm thinking of running a Lovecraftian horror game soon, so I grabbed the free Nemesis rules that Dennis Detwiller, Greg Stolze and Shane Ivey.
Essentially, the rules take the ORE mechanic from Godlike and Wild Talents, add the Madness Meters from Unknown Armies, and adjust them for roleplaying in a Lovecraftian mode.
The game is presented pretty much as a rules set alone. There's no 'how to play' section, no 'GM advice'. There's a brief introduction setting out the overall game, then you get dropped straight into the conflict resolution system, take detailed looks at stats, skills, madness, combat, guns and armor and some ways for stuff to kill characters.
Then the game details building characters, which is on a fairly simple point buy system. This chapter includes a few sample spells and supernatural abilities, suggesting that adversaries can also be built using the same system.
Finally there's a chapter that has stats for some critters out of Lovecraft. They're some old favorites: deep ones, ghouls, serpent men, shoggoths.
So there's not a whole lot to review. I've played enough Godlike to know that the system is solid, especially as this version takes account of the Wild Talents playtests and development, which I know smoothed out a few bumps.
The addition of the Madness Meters is great, I've thought from the moment I first read Unknown Armies that these are the way Call of Cthulhu's sanity loss rules ought to be. In Nemesis, the isolation gauge is omitted - a fair choice, as it is less relevant to this sort of story than it is to Unknown Armies (it's also the one that I remember being least obvious in play, even in that game).
How will it play? We're into the realms of speculation here, although I do have plans to run something soon. From my experience of Godlike, I can be assured that the action parts of the game will be fast paced and brutally dangerous. The madness meters really give a good roleplaying handle on mental breakdown, too. The more detailed view of what is happening to the psyche makes playing out these changes more organic than sanity loss in Call of Cthulhu ever seemed to be. The rules are lean, focused, and mean. They should create some good game.