Aside from obvious issues like not being able to really outrun him and the stamina bar dropping like a lead weight after what seems like 10 feet in scale distance, the transition effects could use some tweaking. half the time I was jumping because of a random tree appearing instead of Slenderman appearing. You could also maybe make the stamina bar heal but only after 5 seconds of standing still. it'd prolong the game alot and you could then que it so that slenderman would appear after a set amount of time standing still. There is a lot of room for improvement but overall you have a solid game. kudos.