Take your time, slide down walls.
Don't blindly faith jump and fall into lava. Pretty easy to dodge once you learn the stage Lol.
"Once you learn", that's the problem, that you have to learn the stage first, and you can't learn it just by looking around from the platforms the level gives you, you can't react to it with normal gameplay and play the platforming game of dissapearing blocks the game is putting in front of you, you have to ignore it and very slowly slide down of all walls. It's cheap design, and that's just for the dissapearing blocks part, because if you try and keep close to the right walls in the following crushing walls section you fall straight into lava, and if you fall on top of the last wall, the one above the lava, you can't see the lava so you either guess correctly and jump far right or you assume you're still in the crushing walls section, jump into the lava and only see it when you can't save yourself from falling into it unless you have above average reflexes, a low latency controller and either the uppercut or the double jump.
On sigma fortress 1 then you have a section with a blind jump with spikes at the bottom that you can't see from the top where there's enemies on the walls, so sliding down is not even the logical guess there.