G'day,

I am working on a set of multiplayer games, where different games play against each other (e.g. you play a Tetris clone, I play an Asteroids clone, but we are both competing against each other). All the games would be based on the same underlying framework written specifically for this project.

I am struggling to comprehend how I would license this so that:

• The underlying framework is open source, so other people can create new games based on it.
• Some games built on the framework are open source
• Other games are closed source

The goal is to have two bundles on something like the Android market:

• One free and open source package which has a collection of games
• Another "premium" (although I dislike that word) paid package which has a different collection of games.

Usually I am fond of permissive licenses such as MIT/BSD, however I would prefer something more in the vein of the GPL for this. This is because for software such as the snes-9x SNES emulator, which is a great piece of software, there is a ton of poor quality versions being sold, whereas it would be preferable if there was just one authoritative version which was always kept up to date, and distributed for free.

If the underlying framework was GPL'd, would I be able to build closed source games on top of it?

Thanks for your input.