Harmony - Troop Symmetry

Well, you can increase the map size; take a look at Heroes of Might and Magic 5.5 – one screenshot shows a map that's 10x18, or something like that, or maybe not... but it's definitely larger than the standard size, and you can add MORE obstacles.

Added 3 minutes later
My apologies, it's 14x14

Well, if you do it like that, you don't necessarily need to reduce the speed, but what should be done with the overpowered energy rune – I heard that to change the rune's effect, you need to modify the executable file (it would be better to either have a fixed speed increase – for example, +3, or +50%).