First off, PC hardware changed. Video cards were the biggest change.The "Graphics Engine" for AoE and AoK was written in 1996 and 1997, with updates in 1998 and 1999. At that time Video cards had 1 Megabyte of VRAM, or even less memory, and were 2D only. They didn't always have 24 or 32-bit color modes, and they had hardware support for 256-color indexed palettes. Direct Draw was at version 1, and Direct X was going from version 3 to version 6.Since then video card have evolved. Today, video cards no longer have dedicated 2D chips, nor do they have 8-bit indexed color support in hardware. They have gobs of memory , and DirectX is at version 11, and DirectDraw has been depreciated.PC Video Monitors have changed. When AoE and AoK were released, all non-laptop monitors were CRT based with 4:3 aspect ratios, and resolutions of 640x480, 800x600, 1024x768 and 1280x1024 were standard. Widescreen was unheard of.Today, you can no find a CRT monitor for purchase, and 4:3 aspect ratio monitors are a tiny, dying segment of the market. Resolutions like 1366x768 now are commonplace.Operating Systems have changed. AoE was developed on Windows 95. AoK on Windows 98 and Windows 2000. Today, Windows XP is nearing the end of its useful life, and Windows 8 is on the horizon.Networking has changed. AoE was one of the first games to use the Microsoft Gaming Zone. Today the Zone no longer exists in a form usable by these games.And yet, you can still play Age of Empires and Age of Kings. Although some help is needed. The video card drivers have to "emulate" 256-color palletized/indexed color modes. And the games do some things, like huge numbers of *tiny* async 2D Blits (so that it would work on video cards with only 1MB of VRAM with 2D chips that couldn't do overlapping copies correctly) which worked back then on 2D cards, but today cause conniptions for 3D cards.The games don't work on all modern ATI video cards, and would crash if it wasn't for the ATI drivers looking for the games by filename, detecting when they are running, and doing special things behinds the scenes to make them run. (ATI users can rename the AoK .exe file and watch it crash to just test). Probably a similar story for NVidia.And though they may work with driver help, they don't always look the way they were supposed to. On windows Vista and Windows 7, there are problems with the new driver model and shell, and you get corruption of the emulated colors. It's not limited to AoE and AoK. Discussion can be found around the net at links like this one: http://go.hopx.net/2010/05/256-color-issues-with-directdraw-and.html And even when the colors are right, the resolution isn't. To fit the new display resolutions, the game screens are stretched, bilinear filtered and otherwise distorted and loose some of their original beauty.