Besiege Review (Slaav)
It's kind of a perfect game. Hard not to recommend
Basically it's a toybox : there are a number of levels that require you to fulfill puzzle-like objectives, but I've spent like 98% of my playtime messing around in the sandbox levels. I'd say it's still a fine puzzle game, but it really shines if you're willing to set your own goals.
The cool thing is that the game is so flexible and deep that after all these hours I still discover new "technologies", new tricks and combinations, that allow me to unlock new possibilities or streamline my existing machines. It's a virtuous circle. Getting better at designing planes allows me to better design my gliding bombs, which means I can improve my bomber that drops gliding bombs, which means I can perhaps stuff more bombs into my bomber or whatever. Looking at my old vehicles, I can see how far I've come since then, and it's immensely satisfying.
I play largely unmodded (outside of a few QoL and UI overhaul mods) and in singleplayer, and I still feel like I could spend years on it.
One last thing : I love the art direction of this game. Most games in the same genre look a bit sterile, but Besiege's "Da Vinci on crack" aesthetic is a great choice, and one that fits perfectly well with the central concept of the game.