2 things: Why not learn a NEW framework? A monthlong jam give you plenty of time to learn new ways of doing things, and is the main reason I personally even do jams, and two, why even post this? you CAN make platformers in Scratch
Yeah but the platformers on SCRATCH are not FUN and not ORIGINAL and yeah maybe I'll try a new FRAMEWORK like cocos2dx or something you know?
Oh yeah its SCROLLING is not that good and SCRATCH doesn't have a Tileset thing to put assets on and stuff so it will be difficult lol.