I play non-historical games. I deploy terrain which will allow (and often direct…) Players to utilize their forces tactically, taking advantage of (or being forced by) the terrain as to where/how they deploy their forces.
I look at the table terrain setup, as the Referee, and I imagine how best a Player could deploy their troops, based on the terrain I place on the table. I try to give each side 'preferred' terrain, in various locations.
For example, if a side has cavalry, most cavalry needs open terrain to be effective (Dwarven Ram Cavalry, and Lizardmen Giant Lizard Cavalry are exceptions, as their favored terrain is Rough/Rocky/Mountainous and swampy, respectively -- they treat such terrain as clear and open, paying zero movement penalties for it).
In my last huge Army Men game, some of the Players complained that the infantrymen were just there to soak up casualties (each side had Howitzer field artillery and Tanks, along with squad artillery -- Bazooka's, Flamethrowers, Light and Heavy Mortars). My rules are designed to generate high casualty rates for fast play. Still, some did not like that.
My next planned Army Men game will take place in a built-up city: relatively narrow streets, lots of buildings, lots of intersections, and Infantrymen will have a relatively easy time destroying Tanks which will have limited maneuverability; LOS will be short, mostly, and most artillery will be useless, or too dangerous because the fighting will be close-in, with (I hope) lots of Close Assaults (hand-to-hand fighting). I expect to really see a lot of Infantrymen Close-Assaulting Tanks in the narrow streets while the Tanks try to turn around. Infantrymen will wreak far more havoc than the Tanks will… Same combat rules, different terrain situation entirely.
I employ terrain to challenge my Players, and myself. They often surprise me how they employ (or fail to employ…) the existing terrain to their advantage. It is part of the fun for me as a scenario designer.
During the postmortem discussions, terrain gets discussed, and I often point out how they might have better employed it, deploying their troops to take advantage of it.
I've used terrain to lure enemy units to come to my units where I had a terrain advantage, and I did my best to augment my unit's strengths enabled by the terrain.
In short, I try to make terrain a key tactical mechanism for the Players to employ to their advantage, if possible, if they see it. If not, there is always the postmortem discussion to point out things they might have missed. Cheers!