Sorry if this has been covered, but I couldn't find a similar topic.
Last night I finally got the Golden God achievement (PC version), but sadly I didn't really deserve it. The game says that I'm at 106% completion, but I only have 94 bandages.
Earlier in the week I decided to finally finish all the warp zones. After unlocking the kid, I should have gotten the "Complete All Warp Zones" achievement, but I didn't. I checked the leaderboard and it said I'd only beaten 305 levels (of 310). I started playing through all the warp zones to figure out which ones I had missed, and after completing the first one in light world 4, I finally got the achievement. I'm POSITIVE I had beaten it before, because I already had one of the bandages from it.
Then last night I decided to wrap up my bandage collection. As I grabbed the last bandage in the warp zone in dark world 4, I checked the leaderboards again and I was back down to 307 levels completed after having all 310 earlier in the week. I was checking my stats and it said I had 102% completion in world 4, but I only had 18 of the bandages. Sure enough, I played through the second warp zone in light world 4 (which I'm also positive was complete) and immediately was bumped back up to 310 levels complete and unlocked the Golden God achievement.
Has anyone else had this problem with worlds other than Hell? Are there any other ways to get over 100% completion because of a glitch? Sorry about the wall of text. And no worries, I plan on legitimately finishing off the bandages this week!