Stage 3 (Hard) : Long Jump 2 times across the middle Stage 4-5 (Hard) : Jump around the ladder on the sides Stage 10 (Easy) : Walk around the walls Stage 12 (Normal) : Stay in the middle and time your jumps to make it across the "lava" Stage 16 (Hard) : Jump across the top of the ladder sideways Stage 20 (Normal) : Long jump sideways on the left block Stage 22 (Normal) : Stay near the middle and jump to avoid damage Stage 23 (Hard) : Walk around the walls again, it's a bit harder than stage 10. Stage 25 (Normal) : Stay in the middle and time your jumps across the "lava" puddles Stage 27 (Hard) : Long jump across 3 of the prisms on the right and jump on the left. Stage 28 (Very Hard) : jump continuously around the walls, avoiding damage. Stage 30 (Hard) : Stay on the right part and jump across the 4 obstacles, only taking 1 hit. Stage 33 (Impossible) : Wall hops around the left or right side of the big block. Stage 34 (Hard) : Jump across the middle only taking 1 hit every second "sphere" obstacle Stage 39 (Very Hard) : Long jump across the second tower to the bottom of the third one. Stage 40 (Normal) : Hold W and Space keys when jumping on the first ladder, and long jump across the middle. Stage 42 (Hard) : Perform 3 Long jumps, at the beginning, middle, and end. Stage 45 (Easy) : Walk across the "lava" puddle in the middle and take 1 hit. Stage 47 (Extreme Risk) : Jump on the first "Grave" to the right and long jump across the middle. ❗WARNING❗ jumping on any other grave will instantly kill you, the one on the right is the only one which doesn't, so avoid the other Graves. Stage 48 (Normal/hard) : Jump across the middle taking a bit of damage.
I hope this could help you in some way. If you are confused about how to do the shortcuts, you can watch my speedrun where I do all of them expect for stage 33 Skip.
Anniversary ending has now been added, since I noticed that its still available in private servers. Ending isn't really complicated so it should be easy enough to beat the ending.