Is this the same as the board game by the very same name?

This is a digital version of the board games, yes!

Can you play with other human players locally (LAN and/or Hotseat) with the offline installer that doesn't have Galaxy bundled in?

This game reminds me a little bit of a game called Ascendancy. What a phenomenal game that was and I would love to see it on GOG at some point.

Got to ask. How is the AI in solo mode?

"Terraforming Mars" sounds like it should appeal to me but does the "board game adaptation" mean each game is a bit short or best played with others?

This board game is easily one of the best made. It's spectacular, and I've yet to meet a person who didn't like it. I don't know about this digital adaptation (which only has one of the expansions it seems), though.

The game is best played with others, but it does (at least paper version) have a solo mode for comparing your score across plays. At its heart, it's about drafting the best cards for your strategy, and building out a tableau to maximize what you've been able to get.

never played the boardgame, but I played this & it's pretty bland.

The AI is OK if you are learning the game, but you will regularly beat it if you are already familiar with the boardgame. AI does not do well with city/greenery placement on the board, too predictable and won't try to block your double/triple greenery bonuses from city placements.

The UI is amazing though. I almost don't want to go back to playing the physical copy because It is so easy to track tags, actions, points, etc...

Anyone knows if it got crossplay with the Steam version?

You have now. Although I must admit that everyone else I know does seem to love it.