In the earliest retail version (.1) of CivDos there's a shift+5,6 cheat to reveal all map and to get some debug options. In .5 version of CivDos this flag still exists (its address: 0xd806), but it's always 0 and there's no way to change it. However all checks for this flag still in the game! You only need set it ON. I myself prefer .5 version - it's more stable and challenging. But until today, there was no way for me to use shift+5,6 cheat in this version. Below are instructions to restore this cheat in .5 version of the game. DO NOT FORGET TO BACKUP YOUR CIV EXE FILE (with different name or in different place) BEFORE ANY HEX EDITING! I replaced option to on/off sound with alt+V. Now game will switch the debug flag instead! After patch is impemented, press alt+V to toggle cheat ON and OFF (message 'sound ON'/'sound OFF' still will be appeared, but sound switching will no longer work). Perform next steps: 1) open civ.exe with any hex editor (don't forget to backup!) 2) find next byte sequence: 83 C4 04 F6 06 C0 19 10 (same with v.03) and replace marked in bold bytes to following: 83 C4 04 F6 06 06 D8 FF (same with v.03) 3) find next byte sequence: F2 03 81 36 C0 19 10 00 (in .03 version: EB 3C 80 36 C0 19 10 B8) and replace marked in bold bytes to following: F2 03 81 36 06 D8 FF 00 (in .03 version: EB 3C 80 36 06 D8 FF B8) 4) run Civilization and enjoy! EDIT: I created patch for JCivED (attached file). Enjoy! Save this file to 'patches' folder of JCivED. Then start JCivED, select Patch, then select your CIV.EXE (don't forget to backup before that!) and then apply CIV1_DEBUG_SWITCH patch. This patch also changes 'Sounds ON/OFF" messages to 'Cheats ON/OFF'. Works only for English version and only for .05 and .03 (but not for .04). EDIT2: you can't interact with AI city screen like in .1 version. M.b. this functionality was patched out in later versions or game uses different flag for it.