AI War is like no other strategy game.
In an RTS or 4X, you basically always fight opponents which are of about equal strength to you. In AI War, you fight a massively strong opponent. This opponent already owns basically the entire galaxy. But the AI does not perceive you as a strong threat, which is why it doesn't just attack you with everything. Apparently it is fighting something in a different universe, after having defeated you. You are fighting small scale guerilla warfare. There is no culture or diplomacy or trade(not with the AI on any level at least. I have the feeling there is a merchant or something?)
The universe is full of gravity wells. The AI owns all of them. They are filled with static defences, and important strategic assets. You may destroy static defences and they will not be rebuilt. Strategic assets will also not be rebuilt. But when you destroy a strategic asset it makes the AI gets a little angry. So this threat(anger) meter of the AI is present on your HUD, and is one of the main things that determines what you do in the game. Taking a whole gravity well to make your base means that you will destroy the local strategic assets and annoy the AI. Destroying only static defence that defends the path you want to take through does not annoy the AI.
This means that you don't spend your time taking all available territory, like basically every other strategy game. I don't know that there is another Strategy game in which owning territory comes with a downside other than them requiring you to defend it based on the resource cost of loss of assets. You take important territory, and cut paths through the other bits.
Static defence has range, or detection ability, so if you leave a static defence that is in a gravity well you go through, but is too far away from the wormhole you want to go through, then it can't actually do anything, as you can manoeuvre around it.
Ships are a different matter. Killing them doesn't increase your threat level to the AI, but they have their own set of mechanics to deal with. I am not fully familiar with all the mechanics. But, in a general sense, it is fine to destroy ships, but it does mean that this will tend to cause a retaliation strike, which you have to defend against, if you engage them and let them escape.
Ships you lose on an AI planet gets converted into material that builds new ships of about equal value that they will send against you later. Though when ships take large scale direct action against you, at certain intervals either because of something you specifically did or just every so often, you will be warned about it in advance.
Your own gravity wells can be filled with your own static defences, which you will need in the incoming waves that operate somewhat like a tower defence.
You and the AI have basically the same set of ships. And ship combat is based around large scale numbers, rather than individual ship control or usage of active abilities. A in, you bring 146 of a specific type of ship, or just a big bunch of 700 ships of all the types. You don't take 2 of your catapults, put them in siege mode, bring down the enemy gate, activate the speed boost on your 6 close range fighters to get into the gate.
You can have a a starting fleet of like 400 ships in the first minutes of the game. And the number of your ships can go from 400 to 0 to 400 in a very short period of time. There are very few resources to manage. The main resources are mined forever in that the resource source never dries up. It's all about massive scale, and constant output of high amounts of ships. This is where the Total Annihilation or Supreme Commander comparison makes sense. The tactics are about massive numbers, not small scale highly specialised units with a range of active abilities.
Also, you can have coop with lots of people vs the AI.
