No JJ2+ features. The other 4 episodes are standard 1.23, so ep5 will also be 1.23. However, if I ever make any SP projects after this (which would be an entirely new thing, not an ep6, since 5 is the last one), I will probably use jj2+.

Also, 900 tiles is indeed long, but keep in mind the level is literally just one long horizontal path. There's very little up and down stuff, most of the vertical space is unused.

Not going to split up the rocks. It does look a little weird when they are bunched together, but if I space them apart, what winds up happening is if you touch the sides of the platform, one of the rocks will fall. The way they are bunched up right now makes them "stuck together", so it is impossible to cause the platform to fall. This makes for better gameplay, which I think is the important thing.

Also, the platform spaces out a bit when the speed increases. The rocks there are moving at speed 2. At speed 3 they become normally spaced (but still impossible to push), making it the ideal speed in terms of looks. At speeds higher than 3, the platform stays solid, but it's spaced out enough that you can cause it to break. At higher than 5 (or maybe it's 6) the gaps become large enough to fall through, making that the maximum speed. If I made the blocks initially start farther apart, I'd be limited to a slower speed in other words.

As for the BG, it looks quite a bit better in motion, since it uses several layers. Most of the stuff you see there is layer 6, but there is some layer 5 in there as well. Easy to tell apart since they move at different speeds, but in a screenshot they blend together and it looks kind of odd. I agree on the black lines though, they are a bit too thin to look good.

As for the layer 8 fade, I'm still trying to find a colour that works good. I want to use a colour that's not found much in the tileset, to give the level a bit more visual flavour, but obviously it needs to be something that doesn't clash.