Allods Online (RU) (381640) reports Steam as not running

Compatibility Report

• Name of the game with compatibility issues:
• Steam AppID of the game:

System Information

• GPU: GTX 1080
• Driver/LLVM version: nvidia 396.54
• Kernel version: 4.18.6
• Link to full system information report as Gist
• Proton version: 3.7-4

I confirm:

• that I haven't found an existing compatibility report for this game.
• that I have checked whether there are updates for my system available.

Symptoms

The game uses a launcher called "Games Mail.ru". The launcher itself works, and can be used to install the game. However, you cannot launch it, because the launcher says that Steam is not running:

It works when you run Steam via Wine, so it's probably related to the fact that Steam.exe is in fact not running on the system.

Reproduction

1. Press "Play" in Steam
2. Wait for Games Mail.ru to appear
3. Download Allods Online or select an existing installation
4. Press "Play" in Games Mail.ru
5. Choose Steam login option

No source file, test, or entry point is identified in the report. Start by reproducing the Games Mail.ru launcher flow using the listed Proton version and system details; done means Allods Online can use the Steam login option without reporting that Steam is not running.