Thanks for the mention Jay since it pointed me to this post.

I imagine you got him the new bundle that comes with Wii Sports Resort. If you didn't , then Wii Sports Resort is a great purchase for him since you want him to be active.

I can mention several games that fall into your requirements:

Red Steel 2 (Action Game. Natural controls thanks to Wii Motion Plus)

House of the Dead 2 and 3 Return (Point and Shoot. Kill zombies, not much story)

House of the Dead Overkill (See above)

Dead Space Extraction (Ditto, substitute zombies with monsters)

Resident Evil: Umbrella Chronicles (Point and Shoot. More story, a bit more complex controls but still manageable)

Resident Evil: Darkside Chronicles (Point and Shoot. More story, a bit more complex controls but still manageable)

Madworld (Action Game. More story, a bit more complex controls but still manageable)

For all of them you should buy him Link's Crossbow Training as well since it includes the Zapper and since it's like holding a gun it might feel more natural for controls and Link's Crossbow Training is very fun as well.

Now, if we go away from the "shoot things" category and forget the "not too cute" one since defining what is "not too cute" would take us forever,  I can definitely sugest the following:

New Super Mario Bros Wii (2D Mario Bros)

SNK Arcade Classics Vol. 1 (Several arcade games for only $20)

Pinball Hall of Fame: The Williams Collection (Again, only $20 and pinball is sorta universal)

Excite Truck (Driving game. Easy to control and very fun)

Punch Out!! (Easy to control and he can either play just with the Wiimote in "NES style" mode or use the Nunchuck and Wiimote to box.

Wii Fit Plus (Great workout game that is very fun and has a lot of activities)

You could also buy him games from the Virtual Console for the NES since those are easy to control and low on story or even get some Wiiware games for him. I can help you with those if you let me know what type of games has your father played before so I can have an idea about what to recommend.

Hope that helps. Tell me if you need to know something in particular about Wii games.

Virtual Console and Wiiware games are also great options since they're cheaper than retail releases (5-15 dollars each) and you can get a lot different experiences that are easy, short and great. Lostwinds is $10 and is very easy to control since you move with the analog stick and use the pointer to move around the wind.

Let me know what type of games your dad enjoys and I'll gladly give you a list of great games you can get him for a total of  $100 and that will provide him with over 120 hours of fun combined.