So I just finished my first playthrough of Invicta and thought I would leave my thoughts for anyone who was curious!
Overall, I really enjoyed this game. I came for the ability to give my train whatever pronouns I wanted, and stayed for the very Drakengard/Yoko Taro-esque grimdark nature of the story. It's not often that you find an RPG where you play a literal hell-train trying to escape a stagnant, dying empire while battling both foreign enemies and the forsaken souls bound to you! I definitely feel like I got my money's worth from this - I played it on and off over the course of several days. The battle mechanics add a nice little degree of uncertainty to things as well.
That said, there were a few snags I hit along the way where I feel like the rules could have been clearer, or the prompts adjusted a little bit more to take into account how you were playing. While this is nitpicking, it did take some time for me to think over how I wanted to handle it. For example:
1. There are some prompts that allow you to consume a soul to "Mark one soul." The rules at the front of the game don't really explain this, or what the consequences, positive or negative, would be, so for the longest time I just kept them. It took reading through the prompts themselves to find out exactly what the purpose of marking a soul was, or what it would mean for my game. (For this prompt in particular where I discovered this, I felt there might have been a typo as well as the task was a little confusing when first reading it.)
2. Some of the prompts may not seem to take into account that a player may be placing the Ace of Hearts at the top of their deck - some of the prompts have you take on passengers or interact with others as if you were still fighting for the Empire, rather than being a runaway train. I wrote these as if my Invicta were trying to fool people or be sneaky, so that might be an alternative if you choose to play this way.
3. The game doesn't state what to do if you run out of cards. I didn't on this playthrough. I'm assuming this would end the game in failure, but again, it's not clear.
I want to stress again that these are nitpicks, for the most part. This is a solid game with an extremely interesting premises, unusual protagonist, and just enough foundation to frame the world, but not enough that you can't go hog-wild with imagination and add what you want. If you're looking for a great solo game to kill some time, pick this up!