Just skimming through the votes, it seemed like people were cool with the arrangement, but not the production. OK, let's see what's up.
Wanted to first say that the guitar & bass work were awesome throughout. The pitched up vocals from :15-:29 don't stand out too much, but seemed too high and slightly chipmunky. Not a big deal as a subtle element here.
Callum's chorused vocals at :29 were such a cool way to arrange the MMX Sigma Stage 1 theme, and not at all what I expected. I couldn't fully understand them due to the way they were produced, but that happens in music all the time, and the tone of everything sounded great. If Callum hasn't heard of him, he should check out Joey Barnes, who does some great original music and whose vocals Callum's reminded me of in some respects with Barnes' track "The Wire (Act 1)."
The vocal gating at 1:24 was an interesting technique, but the way the vocals' volume seemed to drop/duck when the gating happened was odd. I disagreed on the vocals or their treatment feeling too repetitive; they weren't in there that long, and I thought they well creatively handled. As far as the words repeating, it's called a hook; it's fine.
The transition at 2:19 didn't work, IMO. The lead synth seemed so bright compared to the more melancholy vocals before it; same with the whistling at 2:44; maybe it's more of a personal taste thing, but to me the contrast in tones really didn't click there.
Anyway, 3:00 moved onto a section strictly focused on MMX, and the organ and guitar seemed to work better with the whistling-style part. The vocals from 3:27-3:40 got smothered by the guitar work; both of those parts sounded good, but weren't mixed properly to occupy their own space.
If anything, the jarring contrast with the instrumentation & tone of the 2:19 section was the biggest issue for me, but it's also something you get more used to on repeated listens. The other production issues brought up like clutter and clarity were valid and should be addressed, and whether this passed as is or not, it should be improved. That said, the arrangement was very smart and creative, and the mixing didn't bother me enough where I felt parts weren't discernible. There's no way I'd reject this when the arrangement is so strong and the production, while not ideal, was solid enough. I'd love a version with another pass at the mixing, but I'm a strong YES if we only had this version. EDIT (3/28): Forgot to mention, but once I paid more attention, read the sub letter, and recognized the "Never Gonna Give You Up" influence on the lyrics, I was dying. Y'all are some clever bastards.