Do you remember Bridge Builder? I've been in love with games about building crazy contraptions ever since I played Bridge Builder. Hours, I would spend, happily piecing together a 2D bridge out of a small number of parts and then letting a train run across it. If the train crossed successfully, I proceeded to a new level. If it plummeted to its doom, I did not. The tension came from, well, actual tension; from watching as the bridge flexed under the weight of the train and hoping the stress on its joints wasn't about to make it all go a bit Cassandra Crossing. I have no idea if Bridge Builder was the first such game, but it was the first one I found, and it left a long-lasting impression.
So long-lasting, in fact, that when I stumbled upon Rigonauts while browsing Steam I ended up buying it about eight seconds after looking at a screenshot. It's a variation on a theme, but it's rich with potential: using a limited number of parts, you create a 2D vehicle - on wheels, but built around the hull of a pirate ship, because why not - covered in defensive struts and spokes of stone, wood and bone. You then cover it in weapons and send it into battle against an AI-controlled monstrosity that will generally tower over you, protected by its own elemental armour and extensive arsenal of cannons, machineguns and lasers.
You have no active control. You just watch and wait as a nest of bullet and cannonball trails forms in the sky between your hulking, ridiculous vehicles, and sit there hoping that the regular impact of mortars or laser fire on your baby is sufficiently offset by your informed selection of building material - at least for as long as it takes your offensive weapons to unpick the enemy. You can observe the enemy vehicle before you set each level in motion, so you can make fairly informed decisions about strengths and weaknesses and what to build with, and you can also attach targeting instructions to the enemy craft beforehand - an ordered to-do list for your weapons, in effect - but that's it. Otherwise, it's all tension.