We did almost everything we agreed on before hands. We dropped some ideas as soon as we had them by questionning their relevance in the final gameplay as different steps sounds depending on the surface or being able to bait the enemy by throwing items. For the rest, we divided task into "core" and "stretch goals" and implemented the stretch goals after we were done with everything. For example the stress level of the character was added 3 hours before the end of the jam ^^ We all think it adds to the "immersiveness" but it was not mandatory for the game to work out.
I gotta mention the fact that we had some bits of code that we reused from other projects (part of the player controller and the AI were pre-existing) and also that the sound designer and I almost worked full time on this for 1 week straight.