If the skybox causes any lag, which I'm sure it does, I honestly think the level would benefit from getting rid of it. The level is a joy to flow through once you know your way around, and the lag subtracts from that joy enormously.
So, onto the level: I loved it! I've called other levels "organic" before, but this one definitely takes the cake. Most people's slopes feel stiff and artificial, but you actually took the time to round the surfaces up and down and around in ways that I'd never think of. SRB2 has been such a flat-surface-fest for my entire life that I know I wouldn't have had the imagination for some of these curves. You'd think you modeled this level in Blender and not ZoneBuilder! Especially those freakin' arches. I can't tell you how much I love arches. It's not just the slopes, either; it's the way the outdoor areas and caves flow in and out of each other and the way the walls, ceilings and platforms overlap naturally that make this level feel so not like it was made on a grid. The rooms of the level just felt right. It's obvious that you had fun making this map. There's no half-assed areas, no place where you can say "yeah... MK just phoned it in on this room". The creativity and feeling of wonder just never runs out of steam.
I agree with Swift that the pits are a bit too punishing, and there's a particular crack in a platform (maybe I'll post a pic later if I'm not lazy) that sent me down into the abyss not one, not two, but three times! In a goddamn row! I may suck sometimes but I refuse to take responsibility for that one. :P
Also, this level highlights how, um, odd slopes still feel. Maybe this is something that can't be ironed out of the Doom engine. How natural can the physics feel when they're a mile-high stack of engine hacks? Or maybe it's something wrong with Sonic in general, as the more slopes there are, the less I feel in control, and the more I feel like the level is playing with me, toying around with me like I'm a ragdoll in a washing machine.
...Either way, it's not your fault, and the use of slopes is as masterful as I've seen in SRB2... so far!
Other than those gripes, though, I really enjoyed this level. It took me about 4 or 5 minutes just racing down the most obvious pathway, and I knew I'd left a lot of stuff unexplored, which makes me wanna play the level more. The ending came when I expected it, too, which shows a good feel for pacing.
All in all, stellar work MK. You took the GFZ clone and made it your own. It's definitely a worthy sequel to GFZ Holy Trinity.
