what's the differece between "shareware", "trial" and "demo" versions of games (actually of any program) ? If I offer free downloads for a feature-limited version of my game (you must buy a license key to enable all features) what exactly is that called ? demo version ? shareware ? trial ? Also my game has limited features but can be used for an unlimited time. Should I limit time too ? how would it be called then ? I'm a bit confused about these terms... thank you

Shareware usually refers software that requires you to register afer a specified number or days of using it. Sometimes it's enforced by the software becoming inactive afer this time, but sometimes it's not. Paying for the shareware could mean the author sends you an unlimited version, gives you a key or a code to unlock or renable the limited features. It varies.

Demo version software is usually a custom-built version for demonstration purposes, it could be just a single level of the game or it could be a completely new section that is designed to demonstrate a range of the game's features. Demos are usually non-expiring and serve to tempt the user into purchasing the full version.

based on these descriptions, it's likely that you're talking about releasing a form of shareware, but the term itself is ambigous and can potentially cover many different and specific licenses.