Edit: (12/25/2013) Merry Christmas to everyone, now get off the Internet! :3
When the player takes damage, there are 3 main damage types that the player commonly comes across. That being [Normal], [Elemental], and [Explosive]. So of course, the game gives the player options for more defense against these.
When the player deals damage, the game lets them know through colored damage text if they hit an enemy's weakness or resistance. (Instead of DT1's method of ambiguation.) So it's only right that the player knows what they're being hit with. In the demo, this isn't shown, you just get a screen flash. This has changed, instead, the corners of the screen will flash a color based on the type of damage you were dealt. (And it isn't so in your face and intrusive when the player is hit.) The other thing is the game now tells the player how much damage they took like in DT1 and DT2. The color of the text matches the screen flash as well.
Remember this expensive piece of equipment in the demo? It reduced damage from all sources by 1, which is quite useful, a bit too useful. It was changed to reduce damage only from normal type damage. (Basically anything that isn't explosive or elemental (like fireballs)). In every situation, when choosing what type of defensive gear to use, Force Armor was the obvious go to. Why choose only elemental defense when you could go with all of them. (Unless you were stacking them.) This brings back a meaningful choice and removes a late game design issue I was seeing with stacking too many defensive options together.
I mentioned before that it became the final one since Gate 7 was removed, but I never did say what theme it would be using. I still won't, but a not so helpful hint will be given. I've mentioned in the past that it would be of an arcade style, but that's not what it actually is. DT already embraces a lot of arcade style action at times and doing entire set of levels on it is unnecessary. Gate 6 does not represent a game, but instead a genre.
I need to get an FAQ up sometime, not on the game, but on questions asked to me.
It was around this time that I originally wanted to release DT3. Seeing how I'm finishing up chapter 14 of 20, you can see I'm a little behind schedule. What happened? A lot of things, remember nothing ever goes as planned.