I'm not a very artistic person myself, but it would be cool to have a cheesy "alien invasion" mod based on the aesthetic by 50 horror bee movies.

3 factions, the Military which has high armor and high capacity weapons but slow movement speed and lower numbers, Survivor population which has normal everything, but no armor and household weapons (things like mosin nagants, glocks, shotguns, and semi auto long rifles)
And then the aliens, which have high armor, high speed, but low capacity "Every shot counts" weapons like the gun in fallout which can summon down lazer strikes, or stereotypical lazer ghetto blasters.

Just my thoughts to be honest.