Quite often they'll already have several ideas worked out and the team will discuss the options and pick the coolest or most practical one. By now, the team should all be working on the same page. The level designers have a good idea of how the keypad will work, so they start to layout their maps to use it. The artists also know how it will work, so they start making art to fit it. Often this involves opening up Photoshop and whipping up some really crappy programmer art .
Programmer art is cool, because it totally sucks and makes the artists moan and work harder.
The programmer art lets me write up a feature and test it thoroughly without any dependence on an artist. Once the feature is in good shape, I check it into the SourceSafe database and make a new version of the game for the level designers. They test it out and point out problems or suggestions for the next revision. Obviously a keypad is a pretty simple feature and won't require much revision, but larger game elements like new lighting code or a particle system can take weeks or months to finalize. Contact us for more information on GameSpy Industries.