Talk about rapid development
Surely sales of the first Left 4 Dead would still be going well only a year after release? It seems like Valve are shooting themselves in the foot a bit with this - or are they?
Actually, I think this must have been their plan all along. Think about it, they had a bunch of experimental stuff they wanted to test:
- Mass market appeal of zombie apocalypse
- AI director algorithms
- Co-op gameplay where any one person gets completely disabled without their team mates
- PvP where the 2 teams are completely different and have different objectives
- Level of interest for mini updates i.e. new maps/achievements/survival mode
So they make a relatively cheap game (only a few maps, no real story, they already had the engine developed) to test this stuff out. Now that they know it all works well, they can give us a 'bigger game' as they describe it with all these ideas fleshed out.
In summary: Valve's idea-test games are better than everybody else's *actual* games.