I've just played it now [EDIT: played version 1.8]. I can say it is a very well done hack, there are not many bugs or glitches. Here are my comments:
Wood Zone:
SEGA created some of this level (it is available at Sonic 2 beta). This hack contains two acts fully playable, using only original SEGA graphics. There is also a Buzzer badnick from EHZ with modified colors.
The graphics may look ugly, but that's because this level was not finished in S2beta, and the hacker did not include any new graphics. Conveyor belts, which were non-functional at beta, work now.
The Boss is the same as Aquatic Ruin, but with modified totems, modified colors, and also some modification on level layout (there is a roof, so you can't jump high, and there is a hole at middle of ground).
This zone has some glitches at some ramps or platforms. Also, for some reason, enemies do like to fall of platforms. Finally, I got confused when I passed by a post lamp there were already "passed", although I was fairly sure I did not pass it before.
Dust Hill Zone:
This zone features complete new graphics and a "good" and challenging layout. Part of the graphics were based on
the only one magazine preview image (which is not a real screenshot, but a mock-up) that featured a deset level. It also features Desert/Ice transition, similar to S(3)&K Mushroom Hill Zone color (or season) transition.
Sometimes this zone remembers me the Quartz Quadrant, from Sonic CD, because it has some "slower" areas that look like inside a cave, with lots of platforms.
I think these graphics are great, and look as good as SEGA graphics. I can say this level is the most beautiful among new levels of this hack. Unfortunately, I can't say the same about the level layout. I spent ten minutes in act 1, running around, and going nowhere. Then I got bored and tired and enabled the level select and debug mode (they are the same codes as original Sonic 2).
The level layout has lots of springs pointing backwards, some traps, some non-obvious routes and some big buttons that supposedly open or close some passages (like in Sonic 3). I think this level could be a lot better with some arrow signs, like in Marble Garden Zone.
The badnick position is not good. This level has only ground badnicks (triceratops, crocodile, snail), and all of them move similarly. Most of time when you are running, you will find a badnick in the way. If you are not using debug/slow motion/savestates, you won't have enough time to react, and you will bump on them and lose your rings.
Some times, badnicks are at a higher platform off-screen, and you will bump on them just after using a spring. I feel most times badnicks will just get in the way, and you won't have time to see or react to them.
The boss is... huh... I forgot. :)
Genocide city zone:
Completely new level. Since there are no screenshots or mock-ups or anything for this level beyond its name (talking about magazine previews and Sonic 2 Beta), everything here was created by the author of this hack.
The level graphics are good and bad at same time. The background lightning is pretty "lame", and the background night is nice, but not impressive, and not really "sonic-style".
The buildings (foreground) remembers me some Batman game.
This zone is very short, and both acts are equal, except the second one has a boss (Chemical Plant Zone boss), while the first doesn't. The badnicks are also from Chemical Plant Zone.
One bug: if you jump on first red spring, and then fall down, you will fall so fast that game engine will "skip" the floor, and you will die.
For some reason, the bottom half of the level is filled with water, and the water level raises. And I don't know why this would happen to a city. Flood? Caused by what? Rain? But it is not raining. Or by the ocean (like a tsunami)?
Ah, at some places, you can see a ghost. It is just a background graphic, probably intented to look like Sandopolis Zone ghosts in S(3)&K.
Hidden Palace Zone:
This level is present in Sonic 2 Beta, but only half-finished. In this hack, the level is fully playable, although the layout is not awesome (but also does not suck).
The badnicks are from this level. The boss is from Mystic Cave zone, with changed colors (rocks and spikes that fall down look very ugly to me).
It is interesting to note the first "tube" has an "auto-spinning" feature, while the others don't. In Sonic 2 Beta ROM, this feature was not yet implemented.
In addition, the so-famous "
Master Emerald" is present, and is breakable (as it was originally intended by developers, but yet unimplemented in "our" beta). For some reason, there is only one instance of it.
Most of Beta design of this level is present almost unaltered. New places were added, only a few removed or modified. The "
waterslide" is missing, as well as that big slope.
The second act is very small, with very few rings (maybe less than 20).
Death Egg Zone:
This zone is just Chemical Plant acts 1 and 2 (with no boss), plus original Death Egg Zone as act 3. I see no point having to play CPZ again, I see no reason why it was included.
Anyway, the obvious differences are the background change (the space background combines very well with the feeling of this zone) and the absence of water (fortunately, since it would make no sense to have a big part of the level sunken under water).
Conclusons:
Nice hack, very well done. Entertaining to play, specially with level select and debug mode (so you can skip those parts in Dust Hill Zone).
Would a speedrun of this game be a good thing? Maybe. Most of it would be equal to Sonic 2 speedrun, so I see no point in redoing those levels, nor including them to speedrun. I think the best would be to skip original Sonic 2 levels, and do a speedrun only of new levels. Genocide city would be very easy to do. Hidden Palace would not be awesome, but won't be boring either. Wood zone is ugly, not sure if it would be cool. Finally, Dust Zone will be nice to see.
(just one idea) Maybe would be nice to see some speedrun "new levels", aiming for "perfect" (full rings). There should be allowed to use level select to skip 5 zones, and the speedrun could stop before starting metropolis zone.
Thanks for those who read all this. :) :P