From time to time SL may run a beta gameplay cycle of a league using demo software. Such beta cycles end at or very shortly after the release of the commercial software and are only used to refine development of the forthcoming league. At SL all the staff are gamers. Like most organizations there are different skills and skill levels, but at SL all the staff make time to play the games. You may even see the Lead Admin of your league online playing a game.
Games supported by SL also have to be popular enough to support an active community.
SL may maintain a running league that falls below this threshold, but don't expect to see a new game added if there is no evidence of an active playing population.