Well... This is what GURPS does best, improvisation. It's in the name after all Generic Universal RolePlaying System. The 'core' rules merely exist for players to then do what they want... If you've never played it, or invested heavily into what the core rules play like, I can suggest it probably does what you are attempting to do, but with an established, time-proven, tried and tested, and well detailed set of 'core' rules. You want sword fight? GURPS You want alien sci-fi ship to ship combat, GURPS You want a weapon specific to YOUR game, GURPS Submarines fighting scuba-fitted dinosaurs with lasers, GURPS I quote the following from my GURPS Basic Set: Characters (the 'core' rule book): The rules book even states quite blankly that it can interpret any other system or scenario book, GURPS is intended to be a universal translator of gaming, and to me, it sounds like you are trying to reinvent the wheel... I'm not saying stop what you are doing, I've been an amateur games designer for more than 20 years, but what I am saying is you should recognise when the thing you are making already exists, it may be 'easier' simply to adopt into or adapt that thing. So far, in the past 8 months I've run a 1920's gangsters 'city takeover' game, A dangerous-mystery Cyberpunk game and am currently running a game of Fallout... and all using GURPS. I've gone from Tommy-guns and billy clubs to embedded cyber-claws and hack-pads to Wattz Lasers and pip-boys all within the same system.