I may be speedrunning these games now, but I've long been interested in game design. So, in an attempt to revitalize this thread (which is rather enlightening, thanks for the tip on skipping GP1 on Hard) I'll share my thoughts on the subject matter.
To start, I want to go over Keen6's level design as a whole: maybe compare a bit to Keen4/5, but primarily look at it for what it is and how the player interacts with it.
The overworld map in this game is definitely my favorite in the Galaxy games: vivid, colorful, and a sense of progress as you make your way through the levels. There's some lack of detail in a few areas (particularly along the chasm and near the planet/space border), as well as some missed possibilities (a second outdoorsy level would have helped a lot in diversity), but I think it provides the best story through its imagery. There's an overarching goal (find/rescue Molly), but there are several gateway levels, as well as several unique obstacles, that must be passed in order to explore further. (How they're implemented into levels is another matter, of course.) Compare to Keen4's egg-hunt and Keen5's forced but justified linearity. I think, for the pacing of a game, this struck me as well-managed more than the others.
The levels themselves, for the most part, have some problems. As in, fundamental problems. This might have to do with when it was created: there are enough differences between the Vorticon and Galaxy engines, and the map design should reflect that, but Keen6 shows artifacts from the other games (even ideas not well-implemented from those games). Dubious usage of basic pieces, meaningless detours, claustrophobic mazes, and questionable difficulty differences are just few issues. There are also some neat novelties you don't see in the other games that I enjoy and leave a good impact, but these are fewer than the negative.
One of the biggest flaws in this game is an unnecessary amount of cramped spaces. I think levels like
Guard Post Two and
Second Dome of Darkness, and
BASA) highlight this best: looking at the map in full, they remind me of pencil-mazes. You have a lot of areas that give you little to no extra space to explore, becoming more about navigating than exploring. Keen1's Red Maze City wasn't a good level (and please argue this with me if you disagree, maybe in the Keen1 design thread instead) but at least it was intended to be a distraction from the real prize, a secret level, so I give it some credit: Keen6 doesn't do this at all, however, since the mazes are only there to pad the level. In short, you don't want the player to feel forcibly blocked, and there's way too much of it here.
There's also a clear distinction that the some level designs were produced without a clear understanding of the game's mechanics.
Bloogton Manufacturing is the easiest level to point to, with its numerous slanted platforms leading to what I call "infinite-loop ledge climbing" situations. Granted, I actually like the aesthetic these platforms provide, but they were clearly made without realizing the problem, so they could probably have been implemented better.
Really I'd say that there's too much emphasis on "indoors" in Keen6. The first level is great, because we're treated to this wonderful new world, filled with its own mysterious flora and fauna. The next time we get to see any fresh air after that is easily halfway through the game, as we're forced into underground apartments and factories. Even then, most of the open world is only alluded to (GP2, GP3, and even Bloogvile where you'd expect to see more of it) and we're left wanting by the time we hit Bloogbase which, ironically, is more open than the rest of the game! And it's not like Fribbulus Xax is highly-populated and the Bloogs are making use of available space: there is clearly a ton of empty land that could be expanded upon. The levels themselves feel like clustered hubs most of the time, running around in an effort that could be alternatively handled by simply passing around them.
That said, there are some good points in the general design. Bloogville does provide a good sense of terran housing: schizophrenic but considerate (as represented by the arboretum) and, although the gem-required exit is unnecessary, you really feel like exploring every inch of the level. First Dome of Darkness, by contrast, is clearly defined as underdeveloped, with the sparse modules on top and the hazardous disaster on bottom: although you never have to visit half of the level, it's right there when you start and so you're at least curious enough to look around. Bloogfoods is an excellent use of the factory theme, and although there are still some annoying pencil-mazes (and that incredibly frustrating obstacle taunt in the bottom-left) it's pieced together well and stays tense throughout, as it should. Honestly, a lot of the game strikes me as being aesthetically designed without considering the gameplay, which is unfortunate, since it looks nice but quickly becomes bothersome to get through.
Anyway, that's my few cents on Keen6 overall. What do others think of the general flow of the game? I'll leave my thoughts on each level later, if we can get this thread moving along again.