experiment is one of the first classic levels to have proper non-linear progression. experiment is a puzzle level reminiscent of an escape room simulator, with gameplay that loops infinitely until the player finds a way to escape a loop and move on. This concept is ingenious and takes advantage of the natural repetitiveness of the song very nicely, and the looping effect is seamless in every single part. I particularly appreciate how there are no fakes or important invisible objects; the player is given everything they need to proceed, laid out in front of them in a gameplay loop lasting no more than a few seconds, which makes the level more intuitive for the player despite the novel concept. Despite this, the methods of escape are fairly complex and force the player to work to understand them, from cracking a password by hitting orb types in a specific order in a maze to taking a dash orb way up into the ceiling. The level doesn't give the player anything more than absolutely necessary, but the solutions to them are fair and simple enough to find quickly if the player is lucky or attentive enough, making for an engaging and very replayable experience.

My favourite part of the level, however, comes when the song breaks out of its mantra of repetitive loops and expands fully into a synth-based, high energy section, which is where the level's style completely shifts and briefly does away with the puzzles. This feels like a genuine reward for making it through, and it feels so refreshing to play more traditional gameplay. It's not out of place due to the way the song shifts, and it does visually carry over some of the mechanical elements of the previous parts (mainly in the backgrounds), which I like, but even aside from this the chaotic, glitchy mess of crazy effects and flashing colours looks incredible and is one of the most visually stunning parts I've ever played. My only real criticism is that this level lacks progression. Although this is likely intentional, it's difficult for the player to tell when they're approaching the end of the level until they get there. Some presence of the glitching effects, flashing RGB colours or even the hand drawn lineart would have been neat foreshadowing of the level's climax that would've made for clearer progression.

I'm not sure I'll ever quite forgive experiment for how hard its ending trolled me, but I HIGHLY recommend playing through this level for yourself rather than watching a video if it sounds interesting to you. It's one of the most unique and captivating experiences I've ever had with a GD level, due to the challenging but fair nature of the puzzles and the explosive ending that feels oh so rewarding to experience the first time. I would give this level legendary personally due to the lack of clear progression throughout the puzzle sections, but this is still an incredible showing from everyone involved.