I recently had some ideas for TFTD that inspired me to get creative. After working on it a bit, I came up with some stuff. I'd like to hear what you guys think, and if you have any ideas for changing it or not. I'm in the very early planning stages so pretty much anything goes.
The basic idea is to go sort of in the style of my first megamod, patching holes in the original game but leaving it intact as much as possible. This time, however, I'm going for a drastic change: instead of making TFTD a copy of the first game, it's going to be its own thing which fits better into the lore and makes some sense. Old tech didn't magically disappear, so you're going to see some things based on technology developed in the first war.
The idea that I had was to make the land combat easy: you've got a bunch of tech from the first war and it's been developed a bit since the war. The aliens, on the other hand, do best in water. They're out of their element and so it's very difficult for them to combat you on land. Where they excel is underwater. You have no elerium--use of elerium is internationally banned, very few governments have access to it and X-Com can't touch the stuff. Alien alloys have problems when they contact water, so they're available but not always the perfect structural material for every use.
The water problem is not an issue for your flying subs, those rely on the alloys for their high performance on both elements. They simply have layered plating to protect the alloys from the water.
Your coelacanths do alright; the extra plating bulks them up a bit but the alloys lighten them and improve engine performance, ultimately enabling your underwater tanks to perform similarly to the land tanks at the start of the first game.
You can use power armor made from alien alloys on land, or thick alloy diving suits underwater. The diving suits, however, are bulked up a lot by all the extra plating required to protect such a small object from all that water, thus while it's available at the start, it's bulky, unwieldy, and expensive. Once you get underwater, you'll have to make a critical decision whether you'd rather have big armor or better movement.
If possible, I'd like to decrease soldier's time units while in water. The aliens, of course, will move the same on land as in water. Lore-wise, they'd be more comfortable in water but air is just thinner and they're pretty much all benthic so ultimately they won't be slowed by being in air. The exceptions are only in those that can't be on land anyway.
I'm thinking your starter equipment for land combat will include:
Powerful and fast interceptor, slower than old firestorm because it does not use elerium
Fast transport which can carry a sizable crew, good for getting to terror sites
A full range of laser weapons, significantly improved over designs from the first war
Power armor, exceptional defensive capability, no flying (no elerium) (it's a lot like Megapol Armor)
Heavily-armored tanks with potent weaponry such as explosives or lasers
Underwater your best equipment will not be as strong:
Barracuda - capable of both air and water pursuit but not the best speed or range
Triton - can touchdown on land or sea, carries a moderate troop complement and is slow
Harpoon guns are slow and weak but can fire underwater
Dye grenades provide cover
Chem flares are essential for night missions as well as deep missions, dark underwater combat will be very common
Light diving suit has no significant armor but grants best mobility possible
Heavy diving suit has good armor but is pretty sluggish and fairly expensive
If necessary, I'll make land items simply not work underwater. However, there's more nuanced approaches I'd prefer to take:
Gas/Hydro-Jet Cannon and Torpedo Launcher fire straight underwater but have arcing shot on land
Lasers do reduced damage in water
Guns don't work in water at all
Explosives have a smaller explosion radius in water
Some armor types can't be taken into water--aquanauts will simply wear light diving suit if you forget to give them water armor
Land tanks work in water but have greatly reduced time units
Certain alien units are designed for land and are exceptionally strong on land, but are not seen underwater usually (like deep ones, bio-drones, triscenes) - these will actually provide some threat in terror sites - lobstermen are powerful on both land and in water
Floating bases will have a higher cost than underground bases, so your base construction and maintenance costs will be more significant. Your sonars will be plenty effective, however, and you'll have patrol craft available right from the start. Finding the aliens might be a bit easier than before, while getting to them may be a bit harder. I'm interested in a couple things:
1.) More of the ocean is deep. Many times you shoot something down, you can't reach it in the Triton and have to research better diving ships.
2.) Deep alien subs should be harder to detect.
If any of you know how to accomplish some of these more difficult things, let me know. There is a very good chance I'll have to make this in OXCE+.