Quote Originally Posted by PhoenixPhyre View Post
GURPS is one I only have the most passing familiarity with, but I'd probably put it down lower. Somewhere in the 10s or 20s. There are feel constraints (you'll always, from what I understand, end up somewhere on the grittier, death-is-easy end of the spectrum), but there are even fewer genre constraints than D&D. I'd also put the HERO-type systems down there and other "purely generic" games. Ones that are very explicitly "batteries very much not included".
It's worth noting that the 'death-is-easy' feel of GURPS is a product of the system that GURPS uses rather than any sort of tonal choice on the part of Steve Jackson games. It has to do with how the model system that is GURPS functions and unless you distort the numbers massively beyond all expectations it will always be that way. It is a solid example of how the mathematical model that 'the system' actually is constrain game options on a purely mechanical level.

A TTRPG system is ultimately a set of mathematical models (often bad ones), and the structure of those models constrains the possible permutations of the game, including through such things as the choice of dice to use, since different RNG setups produce different output curves. Ultimately any time you use any mathematical system at all this introduces constraints on the content of some kind.