programming grace period

I havn't tried the particular game, but I'd just like to comment that you should never "rush out" a game/engine. Unreasonable deadlines can and will lead to buggy software, missing features, and your team becoming didgruntled and unfocussed. Plan what you want to do, set reasonable milestones (ie. have x-features working by y-date), and then work in order to reach them. Don't push back the milestones, or you'll end up working forever, but make sure they do in fact allow a reasonable amount of time. Don't add new features to the initial design until the end, or unless you have a large ammount of slack-time before one of the milestones.

The short version:
-Set out clear and precise goals (and stick to them)
-Allow reasonable amounts of time for tasks, and don't deviate from this
-Extra features should not be added in such a way as to disrupt the original plan
-Don't rush the work, complete each stage fully and accurately before moving on.