If people want to see what a WW1, WW2, Star Wars, etc mod would look like, just play Barbarian Invasion, turn off limited ammo in preference, then choose 2 factions with crossbowmen units and carriage ballistas. That is what modern warfare would play like on RTW engine.

N2TW works because they're using muskets. And they actually did fought like that in those days, firing in volleys. Note that you cannot make the reloading (pause between volleys) faster, only slower, nor can you make them fire without doing volleys.