Attached games do not start

[jummy0]

When a game tries to load the new dplayx.dll, the process hangs before even opening a window. At this point, dplayx.dll and steam_api.dll are not in use by the game (they can be freely moved or deleted), and the game remains in memory as a zombie process.

I don't own many games that use DirectPlay, but I tried both Speedy Blupi (1998) and DemonStar (1997) with the same result. Speedy Blupi is now freeware at blupi.org in case you want to test.

[gynt]

Are those games that are available on Steam? If so, you can add steamapp_id.txt in the game folder with the Steam app ID, this may help, and then make sure Steam is running or launch the game from Steam.

[jummy0]

The games I tested are not available on Steam; I just added them to my Steam library with the "Add a Non-Steam Game" button.

[Sh0wdown]

It might be a problem if the game is not available on Steam. As @gynt mentioned you can try adding a steamapp_id.txt file to the game folder. Since those games don't have an ID you could try using the one from the "Spacewar" Steamworks example instead:
steam_appid.txt