Players working with BAR gadgets, custom parameters, and lobby presets often hit the same roadblocks. Here is what works and where to find the tweak reference.
Gadgets are Lua scripts inside the game data that handle unit behavior. The evolution gadget and unit spawner gadget are good starting points for understanding how customparams are applied to units. For multiplayer, every player needs the same gadget files installed. Gadgets are not lobby-only tweaks.
There used to be a comprehensive tweak list at bar-stats.pro/tweaks. The site goes through occasional downtime due to hosting issues. When it is down, the alternative is the same URL on the www subdomain. Many popular lobby tweaks come from community members who still have them unpublished, so the masterlist is never fully complete.
If a tweakunit base64 string produces a value error when you paste it into lobby chat, check the padding. The equals signs at the end of a base64 string must be removed before pasting. This trips up almost every new tweak user. Remove the trailing equals signs, paste again, and the command works.
The tweak ecosystem is community-driven. Not everything is documented in one place. When something does not work, ask in the modding channels. Someone has hit the same problem before.
[Crd] The first and only community I have seen that actually holds up to its values. I have honestly not had a single bad experience here.