Whoeoeooooo... Mod is a tweak of original game, but its a separate product. If you play a mod you will be able to play only against people who use the same mod (depending on the implementation ofc).
What you are talking here is changing skins. Just like in TF2 you can change skins/models of player/weapons without impacting game mechanics (for picky idiots, yes changing skins can impact a game mechanics if lets say you change walls to be transparent etc)
I would like to go further in the following directions though.
- Better models (some models like T80U need a change, certain other things)
- Better weapon effects
- Predictor firecontrol/flint missiles
- Minefields and other obstacles
- Networking for arty and air/airdefence systems (both well in the time period)
- Company level AI
We need more missilez code for the missilez god.
"Tactical Ikalugin inbound on this position in 10... 9..."