Some games support custom soundtracks:
Music files have to be .MP3. They can be saved anywhere on the SD Card. You can't do nice things like have certain folders for certain games, it just finds all the music files. You select one song at a time, or tell it to pick one at random.
You can also hack-in your own music to other games:
When I got my Wii I spent a bit of time agonising over rechargeable battery packs. There are a bunch available, but not much concrete info on them. Took me a while to realise that the clear best option is to just by good quality rechargeable AAs, namely Eneloops. You can get little starter kits with a charger and a quantity of AAA and AA cells 👌
Highlights / curiosities from that list (now with notes~):
|Doctor Fizzwizzle's Animal Rescue||-||Disc||Breakanoids|
|The G1 Jockey games||-||Disc||curious how well they work without that arcade cab though.|
|The Garfield Show: Threat of the Space Lasagna||-||Disc||Gotta garf|
|Go Vacation||-||Disc||is pretty cool, just haven't tried it with the board|
|Imagine Fashion Party||✓||Disc||MULTIPLAYER FASHION|
|The Incredible Maze||-||WiiWare||Rollers|
|Intervilles||-||Disc||Minigames, like it's-a-knockout or something|
|Marble Saga: Kororinpa||✓||Disc||Has 30 separate courses for balance board users.||Good|
(Night of Sacrifice)
|-||Disc||horror game by Marvellous|
| リラックマ みんなでごゆるり生活|
(Rilakkuma Everybody's Easy Life[?])
|Rock N’ Roll Climber||✓||WiiWare||rad complex rock climbing|
|Shaun White Snowboarding: World Stage||✓||Disc|
|Shaun White Skateboarding||✓||Disc|
|Skate City Heroes||✓||Disc|
|Ski and Shoot||✓||Disc||Skiing and shooting|
|Sleepover Party||✓||Disc||Sleeping and partying|
(Tokyo Friend Park II Ketteiban: Minna de Chousen! Taikan Attraction)
|Vacation Isle: Beach Party||-||Disc||like Go Vacation|
|Walk It Out / Step To The Beat||✓||WiiWare||walking game where you build a town||Really thought there'd be more control over how you design the town :(|
|We Ski & Snowboard||✓||Disc||Mii avatar skiing|
|Winter Blast: Snow & Ice Games||✓||Disc|
|Winter Sports 2012: Feel the Spirit||-||Disc||It has curling and snow motorbike racing|
|World Party Games||-||Disc|
Wiis are very easy to mod, which lets you do stuff like reenable online services and play, and run games from external drives and the SD card.
RiiConnect is a way to use the online functions of the Wii even though those services are now shut-down :)
It's a simple script you run that generates some files, that you then copy onto your SD card, and install via the Homebrew Channel/
I also had to install the dependencies
xdelta3 to get it to run.
It works for games too! There's a general patch that works for most stuff, but some particular games have their own patch, which does some extra stuff like change text in the game data.
You can easily convert an ISO to a WBFS file with the command-line tool Wit (or using a GUI frontend for it) using the copy command. Simply
wit copy [filename].iso [filename].wbfs will do the job quickly!