By null math, i mean little to no trigonomics, little to no sine calculations, something that a Neandherthal or a Cro-Magnon may understand.
My 2 cents:
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For 45° slopes
In Slope Create event:
execute a piece of code: raiseamount=(Whatever speed you want)
In Slope right key event:
set SonicObj.x+=raiseamount
set SonicObj.y+=raiseamount
set SonicObj.sprite_index=spr_RunR
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There you go.