TLDR
Good grand strategy game bordering on being a MILSIM
Is fully playable in it's current state
Maintains a good level of interest in the early to mid game
Steep learning curve
Some of the mechanics are poorly explained or not explained at all
Lacking towards the mid to late game
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On the front of things, the initial thoughts are that this could be a contender to expand on the XCOM narrative to some degree and whilst it does "borrow" from the same pot, there is actually quite a lot going on for this game that sets it on a very unique path from XCOM.

You start out as one of 7 factions vying for control of the Earth as you face down a first contact situation with an alien species and so, most of the intial focus of the game will be set on Earth as you try to gain the best nations to fund your organisation so that it can reach beyond our planet.

The intrigue during these early stages are positive and you can easily get to grips with the mechanics of the game at this stage without issue. You do have a command point cap which restricts you from exerting complete dominance over the Earth which allows the other factions a chance to reach space but the drawback is that it is fairly easy to dominate the other factions whilst restricted to Earth.

Once you start to move beyond Earth, things get a little more complex...
Setting up your first moon mines is an easy but unrewarding task which is better mitigated by targeting Mars as quickly as possible.
Prospecting and setting up mines is pretty straight forward and so is acquiring the boost needed to reach the destinations as you only have to target large boost countries with the first target being Kazakhstan, who you then get to exit the Eurasion Alliance thus severely hampering the initial boost superiority that Russia has.

Boost is not the only resource you have to focus on, you need research capacity and industrial power.
There are currently three countries that each have unique strengths should you be able to acquire them.

China - Oh the mighty Red Dragon has some issues. It is nigh impossible to break in to straight from the word go, is research is OK, it has a good military and it has a massive industry. If you can break in to it, get the government sorted and the focus moved to research, it has the potential to be the premier superpower but it takes a long time to get in to China which is a big drawback.

India - It has a massive emerging industry, it's research is poor, it's military is limited and it's social issues are numerous and just like China, it's hard to break in to, however, if you can and you have patience, India, with the right moves, can outpace China in every way.

America - great military, the best research capacity and nothing but the sky being the limit. The only drawbacks are getting your initial entry point and the associated cost of holding such a large country, however, out of all the nations, it is the quickest to get in to as you just hold Canada and Mexico whilst rushing persuasion on your councillors and then once you are in, you dump Mexico and Canada but you will be able to come back for them later in the game.
America is the supreme starting point because as I said above, you have the most research capacity meaning you can pretty much control the flow of global research which can severely impact the other factions until they can get in to space.
When coupled with Kazakhstan, you have everything you need to be the first in to space, the first to set up bases, the first to set up mines. In my opinion, there is no better starting point then America and Kazakhstan.

Anyway, when you break in to space, the game moves it's focus away from Earth and the infighting between the factions becomes quite limited with the only caveat being your push towards near space supremacy. If you are the first to set up mines on Mars, you will largely dominate the factions in space.
Having said that, the mechanics of constructing your first space craft are somewhat opaque and not very well explained or documented so you will have to result to scouring around for players who share that information.
A prime example is that in the very early stages, you can barely build craft that can make it to Luna and back but the tooltips then confuse you by suggesting good baselines on delta-v and cruise thrust by suggesting goals that are quite unobtainable at the start of your space rush.
I feel that there needs to be a better execution on how to introduce players to these concepts because I remember on one of my earlier plays how I waited to build better craft to match what the tooltips were suggesting all the while the other factions were pumping out low tier ships to just dominate near Earth Space which made me feel like a right old lemon. Tips should match the level of progress so that newer players don't fall in to this trap.

At the point you really start to make it in to space to fight, you'll enjoy the battle mechanics which follow "real world" principles and then, by this point, you can take the fight to the aliens or run away...but where is the fun in running away?

You'll know enough at this point on how to do everything in the game, however, we also have some small negatives that affect the game other than it's somewhat steeper than average learning curve.

The primary issue is how repetitive the faction fighting becomes on the Earth during mid to late game. This can be quite the irritant when you want to fight the aliens and the other factions are still "rug-pulling" you like really nasty mosquitoes. This leads on to the next issue, there is no resolution against the other factions, you can find ways to dominate them but there is no way to completely remove them which reinforces them as an irritant.
I would like to see mechanics that allow for a mid to late game world purge that allows you to destroy the other factions which then would also allow you to unify the Earth which would fit the narrative of the Resistance faction very nicely indeed.
Earth unity is also another problem, in the vanilla version, you cannot unify the Earth, you can have "extended superpowers" but this doesn't go far enough for me. The whole concept of the factions should rest on their eventual dominance of ideology but the trade-off should be that the aliens should scale in difficulty in a situation where a unified Earth arises, however, this is not something the devs are likely to implement so be prepared to use mods to allow for "faction destruction" and the unification of Earth.

For me , Terra Invicta stands tall as a good game with a few rough edges but considering it is yet to achieve a 0.5 release, it has got time on it's side.

For those new to the game, it's worth a play if X4, MilSim and Grand Strategy games are your thing.

I genuinely hope the devs keep pushing the development of the game and improve upon it's already very solid foundations.

I don't often buy early release games for the simple fact that I like "finished products" but this is one of those times where I've been happy to buy early and I look forward to seeing where the game goes between now and a 1.0 launch.

The complexity can initially be intimidating, but it's an awesome game and can be relatively forgiving. There are certain aspects of this game that I didn't think I would engage with that deeply, but now am hooked on. My only feedback would be to emphasize getting to space faster to the player in the tutorial / initial objectives. Amazing game, looking forward to updates and would definitely pay for DLC.

They really need to get there Federations fixed, so many times i have to reload or undo months of in game time to just fix something that should have never happened. It makes doing African/middle east and i assume south american runs so frustrating.... Makes me not want to play... grats your killed another play through of mine... Ill try again in about 6 to 12 months i guess