I can't figure out how to stop my platforming character from hopping up a steep slope. I've tried bounding box and per pixel and neither helps. I want him to jump on the slope then slide down.
My suggestions for jumping
Disable jumping when on the slope
Give character horizontal momentum when jumping off a slope; enough to subvert their ability to jump up hill.
Haven't experimented with it much
But I think the new "additional velocity" command for platform behavior might be able to help you out on the sliding.