If you launch Assassin's Creed 3 Remastered from your steam library you have a choice wheither to launch Assassin's Creed 3 or Liberation. But if you launch the game via steam shortcut it always starts Assassin's Creed 3. Lets change that.

1. Create shortcut for Assassin's Creed 3 Remastered on your descktop from steam library if you don't have it already. Make a copy of it. You should have two shortcuts. The original one will be for launching Assassin's Creed 3 we don't need to modify it. The copy will be for launching Liberation.

2. Right click on the second shortcut and select "properties". On "General" tab rename your shortcut to "Assassin's Creed Liberation Remastered" or whatever.

3. Open "Web Document" tab. "URL" field should contain string "steam://rungameid/911400". Replace it with string "steam://launch/911400/option2". In russian Windows it should look like this



Using "launch" command instead of "rungameid" allows your shortcut to pick one of launch options.

4. Press "OK" and your second shortcut is ready it should launch Liberation.

This method also should work in every steam game with multiple launch options. You can also check https://steamdb.info/ site for some technical info on steam games such as launch options or command line arguments.