Original Comment by: Jon
I read this site out of interest as both gamer and a programmer, though the programming I do isn't games. I'm a huge fan of formalized design and implementation process. That's how my CRM project team changed a typical 9-to-7-and-then-9-to-midnight day into a more manageable 9-to-5.
Identify a feature as fundamentally stupid, flawed, or impossible?
ROI: you don't waste the time coding, debugging, trying to salvage wasted effort. You may be able to refine the feature without wasting time implementing it the bad way first.
Identify a cleaner, easier, simpler way to implement a feature?
ROI: less code means better performance, portability, less time spent debugging. If someone else has to look at the code for your feature they'll get up to speed more quickly.
Identify functionality you can add to a feature free or with minimal effort?
ROI: your feature's better.
Identify all your integration points and solve API snags before anyone's written a line of code?
ROI: API changes waste time, more or less depending on your programming language and the importance of the change, and are often a headache in source control.
Figure out everyone's tasks and timelines before implementation starts?
ROI: no developers blocked on code that someone else hasn't written up yet, no resource-allocation panic as the deadline looms and you're trying to split outstanding tasks up and assign the parts to unfamiliar developers. Even if it does come down to that, at least the new developer's got an authoritative design doc for reference.
Planning for shorter work days?
ROI: Happy, less-stressed programmers care more about the app (game in your case) they're working on. They use fewer ugly hacks to make things work, and introduce fewer bugs from programming while sleep-deprived. They don't turn a blind eye on bugs and flaws in order to get their feature complete, and can take a little extra time to fix it.
1000% ROI... can adding one day of feature scoping, detailed design, or design review to your timeline save 10 from the other end? I don't know about worst-case, but I've been through scenarios where we didn't do any of this stuff successfully. Yeah I can think of a couple cases where spending a day on Word or conference calls could have - or better yet sometimes did - save two work-weeks of implementation / integration / debugging.