This is my review of the single-player levels:
GFZ1 - 5/10
I do understand that this is the very first level in the game, but should it really be this easy? I always found this boring.
GFZ2 -8/10
It has wide, open space. There are many things to explore, and the platforming is solid. The music adds much to the atmosphere, making it a fun level to play.
GFZ3 - 4/10
It's far too basic. The boss itself is easily ignored and doesn't provide a threat. It's easily dodged, and its ability to run away just makes it even more monotonous than it was in v1.09.
THZ1 - 6/10
It seems too basic. The difficulty is very easy (save for the secret area where you jump on barrels floating in slime, but even that isn't very challenging) and the moving platform wastes too much time. There's a decent amount of things to explore, but the level isn't fun enough to warrant another playthrough from me.
THZ2 - 8/10
This level is a fun level. While I dislike that the difficulty has been toned down in v2.0, it's a fun level nonetheless. It provides a good difficulty level with a good amount of multiple paths and secrets to find and explore.
THZ3 - 5/10
Like it's Green Flower Zone counterpart, this is too easy and repetitive. Little strategy is needed to win besides simply timing easy jumps. I like the idea of placing the player in a tunnel as it's done in here.
DSZ1 - 6/10
It's a bit too easy. I like water levels, but this level doesn't feature anything that interests me. I liked the theme of the level, but the platforming is repetitive in some areas (those ones with large rooms you reach the top of, for example) and the area seems to be lacking detail in some areas.
DSZ2 - 5/10
I just don't remember having fun in this level. It just felt like it went on for too long, and the trial-and-error processes are fairly annoying. I dislike the Zoom Tubes; they just seem unpolished, as seeing Sonic move so sharply and lifelessly just doesn't seem right.
DSZ3 - 6.5/10
It's better than the other bosses. It's not as repetitive as the others, and the idea is neat. However, it's too easy.
CEZ1 - 5/10
It's so...boring. The swinging chains in this Zone aren't very fun to use, and there's several parts where a beginner can get lost. I don't like how you have to jump into a pool to get past a certain area; we suddenly approach a current section without warning, and a very odd-looking Zoom Tube.
CEZ2 - 5/10
This level's boring as well. I dislike the swinging maces and the flame torches; they just force the player to wait, which ruins the experience. I like the puzzle involving a turret and pillars, but the rest of the level feels stale.
NAGZ - 9/10
Now, this is a very good level. It features a great mix of difficulty, platforming, and it has several gimmicks so there's always something in there to spice it up. I like the sheer size of this level, and the massive amount of goodies and secrets to find and explore.
ACZ - 6/10
This isn't much fun, but has its moments. I like some of the platforming sections, but I don't like the rope mechanisms as they're slow and seen far too often.
RVZ - 9/10
Another one of the shiners. It features a good mix of difficulty and entertainment. It has little multiple paths, but the ones that are there are very clever. The level has several gimmicks used throughout, so it doesn't get stale. It looks beautiful and the new textures look great. I like the lava waves at the end, but it's a tad unfair for inexperienced players.
ERZ1 - 5/10
There's a large amount of gimmicks in here. However, some of them simply don't make sense the first time and require the player to lose a life or two to figure them out. The crusher gimmick at the start doesn't make much sense; the player would normally assume that only the red areas should be avoided. The low-gravity hall with moving lasers and death pit floors has the camera pushed into all sorts of awkward positions, messing up the camera. The outer space sections should have less obstacles in the way, and the ending of the level throws you into outer space, and with the ten-second countdown, the player either panics and dies, or can't figure out what to do and runs out of air. The blue safety areas should be more obvious to the player.
ERZ2 - 6/10
It's full of cheap deaths, just like the first. However, the non-cheap gimmicks are pretty neat, but the rest of the level just doesn't feel like fun.
ERZ3 - 5/10
I found this pretty easy. The only hard part is that the way you beat it is just plain ridiculous and requires large amounts of trial-and-error processes to pass. It's not obvious that a near-invincible robot's heat is vulnerable, or that you're meant to jump on spiky missiles that are flown towards you and guide them back.
Special Stages - 7/10
Too easy at the start; the final level is the only one I found challenging. They're repetitive and slow-paced. I like the changing color schemes.
Sonic Robo Blast Remake - 6/10
Pretty repetitive. Even with the engine's improvements, controlling in 2D Mode is still fairly hard to do.
SHZ - 8/10
Another one of the few great levels. It's just plain beautiful, and it's fun to roam around and explore. The different gameplay makes this very refreshing and fun to play; I would greatly appreciate a second and third Act.
Mario Koopa Blast Zone: Acts 1~3 - 7/10
I only found the first Acts to be fun. The rest are just...boring. It's a nice throwback, but the Mario atmosphere is hardly emphasized; it's still the basic run-and-jump gameplay of Sonic.
