A lot of creative concepts in a lot of well designed levels which are over all a great playing experience - but to be honest, I didn't expect anything less 
Let's have a look at the individual levels:
23: A well designed level, not the necessarily the type I personally like the most, but it's a fine one.
44: An interesting concept, I think it would be a really good and fun to play level, if it would a bit smaller, it starts to feel a bit long and repetitive after a while.
52: I like this level a lot, the helmet area is really creative and fun, as is the level over all
The revolving door I pointed out already in the pm, but in the end it didn't feel like it is necessary, it is an interesting puzzle as is. The ball which starts next to the green door is fairly hard to spot with the male tile and the movement of the blocks - personally I think that it doesn't add anything to the level, it might be better without it.
53: A cool concept and really nice level, not to hard yet it starts to get a bit tedious after a while, if it would be a bit smaller it would probably make it a great level.
54: A nice fun puzzle level, really like it
55: A nice difficult puzzle, and as the in the title, obfuscated is the right word, for some parts, even though it felt relatively linear to solve, you have to think ahead a bit in several areas and figuring out how to control the toggle was the hard part, though it's not necessarily one of the hardest levels of the set, and several areas are not as strict as shown in the replay - I didn't use all the buttons available, and I'm pretty sure I got all the chips, so the extra one felt a bit odd for this type of level, it's fine, but I think it would be fine as well if all chips are required.
56: A really good idea, overall the level might be a little on the long side, especially since almost every single misstep will lead to being completely screwed, and the time limit feels way to short, it could be 900 or more. Even though it is relatively linear, it's not clear at the start how everything will work out. It might not be that hard puzzle wise, but you have to explore a lot and at least to me it felt harder than the last level over all.
57: An interesting level, probably not necessarily the most fun to casual play, as the automatic switching even though sometimes helpful, can be a bit annoying. The time limit of 200 feels unnecessary short as you don't have any information about the structure, or where the chips are and therefore have to explore on your first play through.
58: Yes, trial and error with walkers killing you if you make the wrong choice in a maze like structure you don't know (looking in the editor makes it easy, but no). This part feels more like a horrible troll. Removing the walkers on ice however makes it a really nice puzzle level...
59: Under straightforward I do understand something different
, however I really like the fist puzzle, it's creative and interesting to solve The blue tank one is easy, but fun, (in theory you can kill several tanks and make the level unsolvable). What I don't liked too much are the invisible walls, why include this trial an error by removing essential information from the player? At least for me it ruined the puzzle on the left without any reason, normal walls would imo be way better choice (or filled traps or something if it shouldn't be a wall).
60: The start of the level I like a lot, the maze is fine as well
62: Yes, trial and error, not my thing, again a level you don't know the structure and you get killed by making the wrong decisions.
63: The slime part includes some guess work but with educated guesses you will have no problem to solve it, and there are not to many options how to go about it in the first place - it's not difficult - the paths you have to take however are relatively long, overall, but not a bad level by any means, but not necessarily the best level of the set either.
64: To me it wasn't at all clear at the beginning what you can do with the yellow teleport, I think this should be explained on a hint, as it's a really cool idea; sadly the level includes a lot of waiting if you want to play it save, and regardless if deterministic or non-deterministic, which anyhow doesn't effect the casual game play at all, it's not my favorite level, but definitely a cool idea for a blob level.
65: A little tedious but easy enough to be a nice relaxing level.
66: Really cool, I like it a lot, it looks great, to watch the tanks drive in place, and fun to play
67: Really clever use of empty clone machines, the idea of the level itself however really similar to a recessed walls maze with a interesting but weird gimmick, and for such a level type I don't really see how a really strict time limit is necessary or even a good idea. Imo the time limit can be way higher, as this level type by nature has already the requirement of planing a path which you have to figure out through some try and error especially as the vast majority of the structure of the maze is not visible to the player at the start (even though not that complex).
Let's have a look at the individual levels:
23: A well designed level, not the necessarily the type I personally like the most, but it's a fine one.
44: An interesting concept, I think it would be a really good and fun to play level, if it would a bit smaller, it starts to feel a bit long and repetitive after a while.
52: I like this level a lot, the helmet area is really creative and fun, as is the level over all
The revolving door I pointed out already in the pm, but in the end it didn't feel like it is necessary, it is an interesting puzzle as is. The ball which starts next to the green door is fairly hard to spot with the male tile and the movement of the blocks - personally I think that it doesn't add anything to the level, it might be better without it.53: A cool concept and really nice level, not to hard yet it starts to get a bit tedious after a while, if it would be a bit smaller it would probably make it a great level.
54: A nice fun puzzle level, really like it
55: A nice difficult puzzle, and as the in the title, obfuscated is the right word, for some parts, even though it felt relatively linear to solve, you have to think ahead a bit in several areas and figuring out how to control the toggle was the hard part, though it's not necessarily one of the hardest levels of the set, and several areas are not as strict as shown in the replay - I didn't use all the buttons available, and I'm pretty sure I got all the chips, so the extra one felt a bit odd for this type of level, it's fine, but I think it would be fine as well if all chips are required.
56: A really good idea, overall the level might be a little on the long side, especially since almost every single misstep will lead to being completely screwed, and the time limit feels way to short, it could be 900 or more. Even though it is relatively linear, it's not clear at the start how everything will work out. It might not be that hard puzzle wise, but you have to explore a lot and at least to me it felt harder than the last level over all.
57: An interesting level, probably not necessarily the most fun to casual play, as the automatic switching even though sometimes helpful, can be a bit annoying. The time limit of 200 feels unnecessary short as you don't have any information about the structure, or where the chips are and therefore have to explore on your first play through.
58: Yes, trial and error with walkers killing you if you make the wrong choice in a maze like structure you don't know (looking in the editor makes it easy, but no). This part feels more like a horrible troll. Removing the walkers on ice however makes it a really nice puzzle level...
59: Under straightforward I do understand something different
, however I really like the fist puzzle, it's creative and interesting to solve The blue tank one is easy, but fun, (in theory you can kill several tanks and make the level unsolvable). What I don't liked too much are the invisible walls, why include this trial an error by removing essential information from the player? At least for me it ruined the puzzle on the left without any reason, normal walls would imo be way better choice (or filled traps or something if it shouldn't be a wall).60: The start of the level I like a lot, the maze is fine as well
62: Yes, trial and error, not my thing, again a level you don't know the structure and you get killed by making the wrong decisions.
63: The slime part includes some guess work but with educated guesses you will have no problem to solve it, and there are not to many options how to go about it in the first place - it's not difficult - the paths you have to take however are relatively long, overall, but not a bad level by any means, but not necessarily the best level of the set either.
64: To me it wasn't at all clear at the beginning what you can do with the yellow teleport, I think this should be explained on a hint, as it's a really cool idea; sadly the level includes a lot of waiting if you want to play it save, and regardless if deterministic or non-deterministic, which anyhow doesn't effect the casual game play at all, it's not my favorite level, but definitely a cool idea for a blob level.
65: A little tedious but easy enough to be a nice relaxing level.
66: Really cool, I like it a lot, it looks great, to watch the tanks drive in place, and fun to play
67: Really clever use of empty clone machines, the idea of the level itself however really similar to a recessed walls maze with a interesting but weird gimmick, and for such a level type I don't really see how a really strict time limit is necessary or even a good idea. Imo the time limit can be way higher, as this level type by nature has already the requirement of planing a path which you have to figure out through some try and error especially as the vast majority of the structure of the maze is not visible to the player at the start (even though not that complex).
Workshop: Mind Games ++ Test Subject Chip and Melinda Bizarr Chicken Burger
Sets: Mind Games 500
Legacy: GM5 Explorer's Delight Rising
Sets: Mind Games 500
Legacy: GM5 Explorer's Delight Rising