Windows 10 64-bit (16299.64) GTX 1060 6 GB / Driver 388.31 MSI AB 126.96.36.19945 + RTSS 188.8.131.5277 I tried Rainbow Six (1998) and SWAT 3 (both GOG) but the overlay did not show up. I then switched to Medium detection level. This one worked but with major issues. In rainbow six the frame rate was horrible and the game crashed in less than a minute and could not even reach the main menu. It was detected as DD (I suppose directdraw) by RTSS. I think it's a DX5 game? In SWAT 3, the overlay would show up in some instances but not in others. It did not show up in mission. The frame rate in this game was also horrible and unplayable (seemed like single digits but I couldn't get the exact number since the overlay did not show up). It was also detected as DD. This game is DX6, IINM. EDIT 3: It's the OSD that causes the frame rate drop in this game. Disabling it fixes the issue. No need to disable detection. Am I doing something wrong? I don't have such issues with DX11, 9, 8 and OGL games. Haven't tried DX10. It seems the issue is with DX6 and older. EDIT: I just installed Unreal Gold (GOG) and it works fine with RTSS. I chose the DX option in the game and set RTSS detection to Medium. The overlay shows up and the frame rate is at a fine 60 FPS. It is detected as DD. This game is also DX5? EDIT 2: Tried No One Lives Forever and this one works fine too. It's a DX7 game. I suppose DX games older than DX8 are detected as DD, correct? EDIT 4: Also tried the original Deus Ex, which is DX7 I think, and it has no issues, so it seems the problem is with DX6 and older.