You see, Cave Dog Software, who released Total Annihilation back in 1997, set-up the game so that they could later add new units, new AI and maps. Yes, other games have been hacked into 'new' games, but the makers of TA made it a lot easier. As a result, even now, seven years after it was released, there are still communities out there making changes to the game. (Kinda reminds me of Unlimited Adventures in that respect).
Unlike the 'new graphics' in Galactic Empires not changing the feel of the game much, the ability to add new units helps the longevity of the game. By changing just a few units, you suddenly have a totally different game and need a new strategy to win. Following are some of the mods for TA I have tested and some others that I'm looking forward to testing. Some of the mods also take care of some of the bugs in the game left after Cavedog stopped releasing patches.
The game itself is your typical RTS; gather resources, construct buildings, create units, destroy the other side. It has a lot of the features found in newer RTS games as well; build queues, way points, etc. The two teams in the game are Arm and Core.
Arm units are generally weaker but a lot faster. Also, it's usually easier to get an Arm economy up and cranking out units. Core takes a longer to get started because its units are bigger, stronger and slower. Even with the two sides being different, the game provides very good balance and gameplay.
Some Utilities / Files:
TA:Mutations is a custom mod switching utility for Total Annihilation. I haven't actually tested this myself yet, but I'm hoping it will make it easier to change from mod to mod without having to uninstall/reinstall or keep different versions of the game in different folders.
TA:Commander is a newer version of the same concept. The last time the webpage was updated, though, was in 2002.
TA: Conflict Crusher is a handy tool. The problem (at least for multiplayer games) with having so many possibilities for adding units is that conflicts arise between different versions. All the units are assigned numbers, of course, and if two different have the same id number in two games trying to play with each other, the game crashes. So, people came up with utilities like this one to resolve the conflicts.
Cavedog's official 3.1 patch is an essential file that is available in several locations around the web.
Absolute Annihilation 4.2:
Absolute Annihilation was the first mod I tried. The last news entry on the site was from the end of April this year, but that's still good taking into consideration how old the game is. The mod was put together by Caydr and his crew.
This mod (and most of the others) require you having the two official TA expeansion sets installed; Core Contingency and Battletactics. As old as the game is, you can't just go down to your local software store and pick them up. Sure, there's EBay, but who wants to wait a few weeks for it? Luckily, kind people have put emulated copies of all the needed files on the Internet.
The FAQ/Readme that came with the mod was a little helpful but not really. The author tried to stuff it with his own brand of humor which didn't really help much. My first attempt at installing it was successful, though. Although later, after having uninstalled it, I tried to reinstall and it kept crashing the game. So, be careful. Unfortunately, TA AA is not compatible with either TA: Mutations or TA: Commander utilities.
UTASP: Ultimate Total Annihilation Super Pack
The UTASP mod doesn't have as many new units as Absolute Annihilation, the units which it does have are balanced and fun to play with. It also comes with good bug fixes, and beautifully redone graphics for most (if not all) of the units. From tiny scouting units to behemoth mechs, there are a lot of new units that change the gameplay a lot. The mod creators recently released their own custom AI called Banzai AI v3.0.
The install on this mod was a lot easier than Absolute Annihilation, imho. I had to use the Core Contingency data files, but it was basically just a matter of dropping some files into the TA game folder.
Note: I haven't tried the below mods yet, but I thought I would include them.
TAUCP:Total Annihilation Units Compilation Pack
TAUCP is yet another TA mega mod, this one comes with a lot of new units, mostly ground based. It was put together by CyberCewl. Unlike some of the other mods and the original game, the Arm and Core sides are generally similar, with comparable units available to each side.
Genetically Modified Total Annihilation v3
This mod adds around 240 new units to the game. There is a forum for the mod, that seems to still get ok traffic considering the game is seven years old. Glancing around the forum, it appears they're still releasing new units for the game.
Also on their website is a very extensive set of pages, detailing all the units, with pictures of the units.
UberHack:
From what I've been able to gather on the web, UberHack is the mother of all TA mods. It became so popular over time that many subsequent mods had two versions, one for a regular install of TA, and another for an UberHack version of the game.
This mod also changes some of the rules of the game. For example, unlike the original, anti-air units can only target air units. As you can imagine, this changes the early stages of the game dramatically.
Another neat thing it changes are the menu buttons on the build menus. In the original game, when you create a troop producing building, you can position it. With UberHack, you can construct the building so that the troops come out in whatever direction you want.
Total Conversions:
As with other games, TA fans have used the game engine to create entirely new games. For example, there is a Command and Conquer conversion, a Star Wars conversion, and a Dune conversion to name a few.
Not only do you get new units, you get a whole new feeling to the game.
Custom Races:
In the original game you have a choice of one of two sides in the conflict, Arm or Core. Several people, though, have figured out ways to add new civilizations to the game or change the existing ones.
Invasion 2213 changes the races to the Kaje and Xenoclones. While there's not much of a story behind the two new races, it may be interesting to play TA with the two sides constructed a little differently.
(Note: The author of the site recently said he might take the site down as he was finally tiring of 1997 graphics and thought TA fandom was dead. ;)
A race that's available in addition to Arm and Core is The Lost Legacy. This race addition has a story behind it for those who are into those kind of things.
Conclusion:
Yes, it's an old game, but it's a classic that is still fun to fire up every now and again. With a player base that is still somewhat active after seven years it's easy to install a mod and play a somewhat different game.
I couldn't find any abandonware versions of the game on the web, but I'm sure they're out there if you look. Or, you could check the sale rack at one of the big chain stores or try your luck at EBay.