Single player, by 
Several hours passed since you had uploaded this, and I’ve already come out with a first review.
PROS
I appreciate your attemps to invent new mechanics and eyecandy. For example, those burners that heat the iron platforms so you can’t step on them without loosing one heart, some tricks with springs and an unobvious way to reach barrels in bonus room. In my opinion, this level is a lil bit better than Frosty Party since it is not crouded with respawning foes. And I’m glad that at least there are no bees and beehives in this abandoned chemical laboratry (unlike they were included into your winter level).
CONS
The begining of the level was so nice, so similar to original levels, that I was filled with hope for an equally decent continuation. However, all of my hopes were smashed when I faced those sadistic things you love to place in your levels. Now, let me list some of that issues:
-Numerous areas where you have to search for an exit for a long time or search it by looking up in JCS. This significally reduces the pace of the game and thus the conception of a fun and fast shooter is been ruined. Majority of the players won’t solve your puzzles, they’ll use cheats or even give up without trying.
-And again, those annoying pits that make you cheat to get out of them. That’s definetly not good.
-Maybe that wasn’t the only way, but once I had to kill floating lizard and capture his copter to go further. Probably it’s not the best decition as the lizard isn’t respawning, is he?
-Invisible Dest Scen blocks. The idea is good, but, as you can see, it’s easy to get stuck into them.
-Finally, I expected to encounter a boss, but there wasn’t one.
COULD IMPROVE ON
You should think how to improve gameplay. Maybe it would be better to make player solve puzzles in order to reach gems, while progressing through the level would be a way less exhausting? Thus the player will be able to choose whether he wants to relax or to complete a challenge. Few words about the pits in this and some other of your levels. Even if you were not going to use script you could increase the depth of pits and place two rows of CTF bases (row of blue bases and row of red bases) to their bottom. Actually the collision with them kills you in single player mode.
Good luck in future works!