Nothing beats a classic. This is the game that really started my love of games. There is nothing about this game that doesn't define the genre it helped create. It is one of the originals and every designer should be forced to play this game. Only games that can be as creative as this should be made in the future.
The game is simple, it doesn't have a lot of bells and whistles. What it inspires is a sense of adventure. It basically sets you in a world and tells you to go. It doesn't tell you where to go and when to do certain things. It's up to the player to figure it out. This is what modern games are lacking. Sure you can challenge a player with difficult challenges and impossible odds but this game does all that and achieves something modern games miss, it's fun.