The installer version of GraviNULL Open Alpha: a1.0 Simply run and click next a couple of times to install it. Afterwards restarts steam in order to make the mod show up on your games list.
This zipped version is for those that have troubles with installers, or prefer (zip)archived files. Like most, if not all SourceMods. Simply extract to the SourceMods folder and restart steam to have it show in the games list. Or use the installer
In GraviNULL, the player will be put in a Zero Gravity situation with no means to move around besides using a modified gravity gun with a "grapple" function.