Brimstone is a set of d20 RPG rules which was abandoned during development. Rather than hide it away, we've decided to release the unfinished product as PWYW as it it technically playable with some improvisation, and at the very least might contain a variety of ideas and conent which may be useful to transfer into your other games.
The game uses a classless system, where you craft your character by combining individual skills and feats. However the skill list, feat list, and many other elements are streamlined, as the emphasis is on roleplaying, exploration, and survival over endless rules.
The mechanics are based on d20 systems, with some simplifications. Combat is grid-less and mini-less by default, but could be modified easily to use either. Although spell descriptions are included, there are no monsters or magic items; development didn't get that far. You could use easily use any monsters and magic items from another d20 product though, or simply make up your own on the fly.
Hopefully some of the ideas in this file will be of use to you. Take a peek!