Today I will speak about two things, the water levels and the Chaos Emeralds function.
Since water levels exist since the first game, of course they had to be included in the wad.
When you are underwater, your movement speed is way lower, but you can swim and go wherever you want. But Doom Guy isn't a fish, and so....
Yes, you need to breathe. As you can see on the screenshot, there are some "Bubble Box". You will be able to stay underwater a few more seconds each time you pick one. Unlike Sonic, you won't get instakilled if you are drowning, your health will only get depleted slowly... and then faster.
So beware the water levels, because they will give you nightmares !
2. The Chaos Emeralds
First, look at this screenshot :
This is the Sonic 1 Special stage. Each Chaos Emerald have his own special stage (based upon various Sonic's games), and you'll need to complete them to get a Chaos Emerald.
Of course, to get there, you will need to find a secret exit. 7 Chaos Emeralds, so, 7 secrets exit ? (or more, who knows... :) ). Since the wad works with a hub system, you will be able to go back into levels you have already completed, to find these in case you missed them.
But then, what do we do with the Chaos Emeralds ? Please look at this screenshot :
The Shotgun design is still in WIP. Anyway, you may have understand what it means. Each time you find a Chaos Emerald, one of your weapon will get upgraded, and get stronger in many ways.
It would be weird to have the Doom Guy transform into "Super Doom Guy", since he doesn't know what these Chaos Emeralds are.
All the weapons can be upgraded, except the Chainsaw and your punch. So yes, the Chaos Emeralds are a valuable resource to help you in your adventure into Sonic World Doom.
That's all for now, see you later :).