Long post ahead. I decided to post this in KeenModding rather than on the PCKF because I included a lot of modding advice. I gave this mod a single playthrough, and for a first mod I'm very impressed. This is 10x better than my first attempts at modding. (see
http://pckf.9thfrontier.com/viewtopic.php?t=1827)
In general, you seem to have a lot of great ideas, and I think you have a lot of potential to be a great modder. However, before you move on to new things, you definitely need to look back at what you've completed here and see how you can improve. You still have a lot to learn about level design, tiling, and graphical edits. Try to master these areas by fixing up this mod as much as you can. A few areas you should consider:
Tiling: Every level suffers from misplaced tiles. In particular, ceiling tiles need a lot of attention. As tricky as they are, Keen 5 does provide the proper tiles that get rid of the extra lines on corners. Use them. Also pay attention to background tiles. In many places, you get a little sloppy with using their patterns correctly. I know that you tend to skip over these little details just I like I used to, but fixing them improves your levels a lot.
Clashing colors and clashing backgrounds: A lot of the backgrounds throughout your levels don't go together well. In particular, the recolored red background that you use frequently in levels such as the laser towers tends not to blend well with the rest of the colors in the game. Also, be careful about using too many different kinds of backgrounds. I have discovered that using fewer different backgrounds generally makes your levels neater and more visually appealing. Levels such as Guard Three could benefit from less background variation.
Ceiling and wall thickness: Guard Three provides an excellent example of what you could improve in this area. Generally, you should have at least 1 ceiling tile below platform tiles, and vertical walls that have at least one solid tile in between the left and right edges. These rules can be tricky to follow sometimes, but doing so will also improve your levels.
Archways: Also using Guard Three as an example, you've probably noticed how there is a single column of background tiles that shows up on the inside part of the right edge. While you tend to use any background tile you want here, the correct tiles to use are solid grey for the top parts and the correct platform top for the bottom. If this doesn't make sense, I can try uploading a picture. Take a look at the arches in the original Keen 5.
Points: Placing points well in Galaxy can be much more challenging than most people would think. I used to place points in every free space I could find, but now I realize that it is better to have less of them. There are a couple of rules you can follow to improve your point placement:
1. Try to avoid placing high value point items (1000 or more) in very easy to reach places. If the player can just grab high value points without any effort, then those points tend not to seem as valuable. Another good rule of thumb is to make your levels beatable without collecting any or very few points.
2. Minimalize excessive point grouping. For instance, in The Shikadi Room you had that section with tons of 100 points items as well as a huge drop with tons of vitalins to collect. Instead of completely removing these, try thinning them out.
3. Don't place points together with keygems or right next to other essential things in the level. If the player has to reach those things anyway to complete the level, why provide them an extra reward?
Test you levels: I realize that you didn't exactly have time to do this with the Keenday deadline, but thoroughly play through your levels, checking every last inch and correcting any bugs you find. Try to think of playtesting your levels as fun rather than a chore.
Once you improve the execution of your ideas and become more familiar with how to manipulate things well, you'll find that your work will become really amazing. If you take the time now to get better at little things like tiling and design, you'll be able to progress towards making a high quality full mod much faster. Trust me, you'll thank me later if you follow this advice. The more thought you put into modding theory, the better your work will be. Ceilick had to invest a lot of time into this stuff in order to make TUIT as good as it was.
Again, great job on this. I definitely have to compliment some of the original ideas you had. My favorite level was the First Lasertower, though some other levels were pretty clever too. I particularly liked the way you ended the 4th Lasertower with the same room as the original game. The more creative you get (provided you execute your ideas well), the better. Although I think you yourself should be the one to go through this and improve on the areas I mentioned, I am willing to help with the revisions this week if you want me to. I already know some ways that some small details could be improved (such as the lasers on the world map). I hope all this helped (because it certainly took a long time to type).