When a friend of mine suddenly decided to buy an Amiga instead of a C64 in 1990, I was very curious what the games would look like.
The first game that completely blew me away was Aladdin's Magiclamp. A horrendous horizontal scrolling shoot-'em-up by todays' standards (let alone in 1990), but the sound of breaking glass when enemies were shot really amazed me.
It was UBI Soft's Unreal which made me decide to work overtime and use all of my pocketmoney to get an Amiga. The 3-D graphics were amazing and the arcade adventure sections looked beautiful. But it was the intro-tune that really sent shivers down my spine... Anything was possible with the Amiga!
When I load up Unreal nowadays in WinUAE I still get that wonderful feeling. It still is an amazing game after all those years. *sigh*