whatever your movie is, i suggest no dialouge and have the camera be extra kinetic.

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i have an idea, it might be what your looking for, it might not.
I did this once in high school.
get a serious topic that effects a lot of people and then pitch that to them (maybe controversial) then shoot their reactions and conversations about it for hours, then edit it down.
I think conversation pieces are great to do in 24 hours.
action takes time, horror takes time (unless you did a sort of real-life slasher in chronigolical time, that could work ie. blair witch)
conversation 24 hour chrono. example Coffee and Cigarettes by Jim Jaramuch
horror 24 hour project example Blair Witch or Session 9 (i don't know who made session 9)