Three-dimensional strategy

Majority of strategy games are limited to a 2D plane despite the fact 3D graphics have been used for ages.

The most you can see deviation from this is the addition of aircraft and some gameplay elements regarding elevation or layers, but all this can be done in 2D. Essentially all strategy games can live with a height map alone, there are no overpasses or similar that place a unit above someone (not just higher than them).

The lacking is especially egregious in space strategy games, for which we even have a specific tag for (see: flat space).