make creep upgrade a single purchase

[GooglyBoogly]

advantage for upgreating only armour is:
- creeps get stronger
- you can buy better tanks
- the force is feeding less on the other force (more income alone for you)

advantage for upgrating damadge(too):
- mines get stronger
- cheaper than armour
- may kill some opponents too espacially if force is used in mass

mh dont know, but i think its rather good balanced. The main upgreater for damadge are trader and mine players.

you forgot that explosives/bomb get stronger too. Increasing damage also makes mortars stronger as well.
An unmentioned armour advantage is that it boosts bunkers and factories while damage confers no advantage to those buildings