We have one of these topics once a month, don't we?
I'm from the Atari VCS generation, that's the Atari 2600 to you punk kids. And while I do like that system, I have even more appreciation for the Mattel Intellivision. It tried to have very different style of gameplay. It ultimately succumbed to making was was popular before the end, but until then, it had some really different games that tried to make the most of the keypad controllers. Not to mention the Intellivoice add-on which was fairly decent for the time and they actually worked to make the voice integral to the game.
EDIT: Forgot to list some games.
Adventure, Beamrider, Demon Attack, Frogger, Haunted House, Infiltrate, Joust, Kaboom!, Keystone Kapers, Laser Blast, Laser Gates, Missile Command, Montezuma's Revenge, Moonsweeper, Ms. Pac-Man, Pitfall, Reactor, River Raid, Stampede, Star Wars: The Empire Strikes Back, Starmaster, Turmoil, Yars' Revenge for the Atari
ADVANCED DUNGEONS & DRAGONS Cartridge AKA Cloudy Mountain, Astrosmash, B-17 Bomber (Intellivoice), Beauty and the Beast, Bomb Squad (Intellivoice), BurgerTime, Buzz Bombers, Dracula, Frog Bog, Ice Trek, Shark! Shark!, Space Battle, Space Hawk, Space Spartans (Intellivoice), TRON Deadly Disks, Utopia for the Intellivision