Some pages within this website (including the download and browse pages) do not load, simply saying "General server error" and leaving this error in console: powdertoy.co.uk/:1 GET https://powdertoy.co.uk/ 500 (Internal Server Error)
The front page formula broke down and started throwing an error. Whenever the front page is stale, the website tries refreshing it the next time someone loads it. (Which also means front page will never change if nobody looks at it ...).
Since the formula was broken, everyone that tried to load the download or browse pagaes got a 500 error as it tried to recalculate FP. The formula is a combination of upvotes, downvotes, and age. One save had just the right values to break it.