It's definitively one of the most technically impressive hacks considering it includes a colour shader (which allows for a more realistic darkness, for example), 3D parallax, a custom title screen and file selection and entirely new playable characters.
Most of the time, the level design is quite fun. In particular, I really like Fuzzy's Ridge and Mushroom Gorge as level.
The weirdest level is Rex Village, considering it is one of the longest ones, though I think it makes sense when you consider that it normally would be a hub level if you were aligned with the Rex.
The weakest levels IMO are Dinolord's Domain, Evernight Temple and Castle Rex are the weakest levels, if only because they are so linear as well as the fact that they can get quite spammy at times (well, I really don't like the buff rexes and they come up in the former and latter quite often).
Now we get to the controls: It's expected that. Mario is largely unchanged but even he has got some changes in physics and controls (for example, picking sprites up requires the press of the run button and holding isn't sufficient anymore) while Luigi is quite difficult to control due to being floatier than Mario and the tornado ability is also a bit difficult to use (though it becomes less bad when you know that you can stop the attack with another A press).
Though I already know the controls from the older demos, Kabaal is a completely beast considering he uses non-standard controls, playing more like a beat 'em up character than a platformer, not to mention he jumps higher when not
moving while it's the opposite for and Mario and Luigi. I find it cool that you can go into a shell when running, though you can't hurt enemies that way when you can in NSMB (I know, it's in the end your decision but still) and the different swimming physics is also quite cool, considering that also isn't seen very often.
What also is cool is that you have. For example, there is that one Dragon Coin which can only be gotten by Kabaal because he can dash straightforward i.e. without falling.
What I also really like are the animations. A lot of enemies have got quite a few animation frames and even idle animations (e.g. buff rexes) and if there are accessories (such as it's the case with most of the rexes in the village), they may even get dropped. Other cool details I noticed are the birds (though they already exist) and bushes.
Music is also often quite good. Only the title screen and Dinolord's Domain music feel if only because of the slow intro. The death theme also feels rather underwhelming.
Also some spoilers when finishing the demo:
What is interesting is that the tutorial level, which showcases Mario's fireball ability, features one of these shadow creatures which were shown in the older demo. I assume that they're created by Dark Lord whom King Rex made a deal (which also is some interesting forshadowing). The same level (of the older demo) also features Wizard who presumably use the same source of power.
Some suggestions: I think it would be cool to have the mountains in Rex Reef Beach be covered by the water so it really feels like you're underwater. The same level also has got falling Rexes at some point which IMO should be alerted with some arrows since it is very likely one could hit the character by pure chance.
I also would have liked if the buff rex at the end of Rex Village only would hurt you if it jumps and not when it's coming right out of the statue.
And now some really not-so-great stuff:
- You can hardlock the game by throwing a shell to a shield as it is possible in Evernight Temple. This may not always happen but considering it really did once, you should consider taking a look at it.
- You also may want to fix slope interaction since I managed to softlock myself by clipping through slopes by pure accident (I know, this applies to vanilla SMW too but here it's especially notable with Kabaal).
- Not a softlock one but still annoying: You can get stuck on the overworld if you run towards the topmost river tile near the bridge to the beach. Not a softlock because you can still use the pipe but still noteworthy enough to be fixed.
- I managed to get Mario killed simply because a chest landed on top of him, essentially crushing him. I don't think that's a very good thing happen, especially with open chests.
- Finally: Is it normal that when you get a star, the characters randomly start performing the action of the A button? At first I thought it was my controller but it turns out, that really only happens when you get a star.
I used BSNES v115 to play the hack so some bugs may be emulator specific.