Bought a Gameboy Color. Any game suggestions?

[TrevDaRev]

I saw a pretty good deal for one on eBay so I purchased it, its a Yellow one, with a yellow GB protector, Offical Nintendo carry bag, 3 games (Donkey Kong Land, Donkey Kong Land 3 and Donkey Kong Country) plus 3 plastic game cases to keep the games in. All for £29.

I've bought The Simpsons Night Of The Living Treehouse Of Horror (remember a friend having it back in primary school & I had a blast playing it) & Buffy The Vampire Slayer..:P

I was just wondering if theres any games you would recommend or class as essential buys.

Thanks.