Using terrain for defense?

[zaphat]

So I ended up near a nice valley in my new military scenario.
My question is on what slopes can the bugs descend?
Is the rule: if walls can't go there neither can the bugs, or something more complex...
My idea is that I would only need to defend from one direction instead of a base out in the open.

[Jaggid Edje]

So far, when I built with the assumption that "if a wall can't go there, neither can the bugs" it has worked.

I won't go so far as to say that it's an actual rule, but it has been effective for me thus far. I have used the terrain to some degree on every playthrough.

On my True Solo run, which I recently completed, I saved myself a bunch of time needing to build my 'maze' by using a pond as one stretch of the maze wall, for example. And the 'rear' of my defensive bunker was a cluster of big rocks.

Added advantage of using the lake/pond...it doesn't block your line of fire at all.

[Cotaks]

The only defense is a killbox or water.

Killbox is just the best way, they walk in/to it from any direction, water blocks bugs from getting to point b, flyers dunno if water stops them, never tested due to i dont like to build against water/mountains. However mointains are not a defense option, bugs and your people can walk up very steep cliffs.

[BobThyAsian]

I initially liked playing around areas that had large impassible rocks that could be to as fortifications. I tried using hills that same way but then I saw one of my survivors walking up a hill so steep I thought he'd fall.

Now I like big open flat spaces. And why reinvent the wheel when it comes to defensive building. Get medieval! I use floors to make ramparts behind my fortified walls. And fencing in front of the wall with gates used periodically to act as a firewall.
https://ibb.co/JQFMYjH

[zaphat]

Thanks for the replies guys!

"why reinvent the wheel when it comes to defensive building" - well TBH, I play games to be able to reinvent wheels: there are simply not enough oppurtunities like that IRL.
But then if you spend a week on your wheel and it turns out you can't use it on this planet, that's what I hate.