Ensure you have the full 0.5.4 version downloaded. If the file size seems unusually small (a few MBs), it may be corrupted or an "update-only" patch rather than the full game.
Once extracted, open the new folder and look for the executable file. File: TheSinger-VER_0.5.4-pc.zip ...
As an early-access (v0.5.4) title, bugs can occur. Use multiple save slots before major decision points. Ensure you have the full 0
The The Singer Guides page often contains detailed walkthroughs for achieving specific endings. File: TheSinger-VER_0.5.4-pc.zip ...
Double-click The Singer.exe (or similar .exe file) to start.