Examples of existing client-side mods:

• Replacing a map's map.png to mark potential special crate locations, possible ice cream spawns, cargo vehicle locations, etc
• Increasing a weapon's sight_range_modifier to see further away
• Removing screen shake for better shooting control during artillery strikes (and other blasts like C4)
• Scaling loot meshes and/or modifying loot textures for improved visibility
• Renaming special crates so that they show their contents in their hover-over text
• Adding additional ladders to maps
• Tweaking animation frames to add more push "commands"
• Modifying weapon sounds so that rare weapons are easier to hear on the battlefield
• Adding/modifying item_containers
• Reducing fog density for improved visibility 👀
• Modifying los.png for improved clarity regarding when a shot is blocked by terrain/trees/etc
• Modifying artillery circle marker opacity for improved visibility (especially in snow maps)
• Modifying terrain texture colours (e.g. to make Tropical Blizzard less blue)
• Adding <addon_model> to weapons (e.g. showing a rocket on soldiers' backs)