[Research]

example)
Surgeon's Stahlhelm + Physician's Procedure Mask + Blutsauger
= set effect: Heals 10 health points on hit

I tried modify items_game.txt is not working

[Powerlord]

items_game.txt is only there for backwards compatibility with plugins. TF2 itself now uses the Item Schema that it downloads (as XML?) periodically from Steam servers.

[Leonardo]

Originally Posted by Powerlord (as XML?)

as VDF, I guess.

[Velture]

It was once able to be done via editing items_game but it was abused by idiots who wanted to use this as a cheat on ClanWars giving some extra dmg to their weapons without usung tf2items.