Steam (just in case)
You can enable "Display Steam URL address bar when available" on Steam > Settings > Interface:
After that you will be able to see the game ID on the store page (in this case, 236870):
uPlay
If you have a game shortcut on your desktop or start menu, this will contain the uPlay Game ID on the "uplay://launch/ID/0" format (in this case 54).
Also you can search the game ID on Alex or Haoose GitHub repositories.
Origin
Origin have game ID's, but most of the time they are not used. You can still launch the game that you want with origin://launchgame/ID.
To get your game ID, head down to C:\ProgramData\Origin\LocalContent and search for a folder called like your game:
Open it up and there should be 3 files that start either with "DR" or "OBF-EAST":
Just add : between the last word and the numbers, that is your game ID (OFB-EAST:46851). Now just use that to launch your game:
origin://launchgame/OFB-EAST:46851
You can still launch the game from the main executable for certain games:
Just to make sure add the path of the Origin executable at the end (useful for launching the game via Steam):
"E:\Origin\Need for Speed(TM) Most Wanted\NFS13.exe" "C:\Program Files (x86)\Origin\Origin.exe"
Battle.net
The Blizzard App also does not use ID's, but you can launch them via network protocols (recommended):
"C:\Program Files (x86)\Battle.net\Battle.net.exe" battlenet://GAME
If the app is running, you could just do:
battlenet://GAME
You need to set up the game that you want to launch on the URL:
World of Warcraft: WoW
Diablo III: D3
Starcraft II: SC2
Hearthstone: WTCG
Heroes of the Storm: Hero
Overwatch: Pro
Starcraft Remastered: S1
Destiny 2: DST2
Call of Duty: Black Ops 4: VIPR
They also can be launched via the "GameName Launcher.exe" file (for example, "Overwatch Launcher.exe") but that would require pressing play on Battle.net: