Wii Sports (Wii, 2006)

This is the best game out for the Wii. You wont be able to find it at most game stores, because it only came bundled with new Nintendo Wiis. You can find more than a few here on eBay, but they arent cheap.

The games are alot of fun and there is so much variery. Wii Sports comes with 5 games in one:
Tennis - You swing to serve and return the balls and you can put your own topspin or downspin on the ball. This takes a bit of timing to hit the balls where you want them.
Bowling - My personal favorite. Lets you put left or right spin on the balls, just like real bowling. How fast you "bowl" will depend on how fast you throw the ball.
Baseball - Another game that takes alot of timing. Batting is alot of fun and you can crank homeruns like crazy. Just watch out for the nasty change-up pitch.
Golf - Where and how far your ball go all depend on swing speed and accuracy. Putting will take a little time to get used to, but very entertaining. The downside is that, there is only one course you can play.
Boxing - You may break a sweat playing this one. You have to dodge opponents' punches and counter-attack when they are weak. You can jab, uppercut, or give a hook to knock em down. This is the only of the 5 that require the numchuck attachment.

This is a fun game and everyone and even little kids can get into the action. A great family game all around!