Thanks for all your suggestions. What I want is to hide the games completely so that he doesn't even know they are there. If he sees something then he'll want to play it!
I'm clear on parental controls. Games are set to 7 and below. Freeshop requires the parental PIN, I assume as it needs a net connection, which I've also turned off.
It sounds like a separate emunand could be promising - I think I know what this is. From my limited understanding I think it's like booting up and mounting a different hard disk on a PC. I seem to recall seeing an option to switch emunand when I interrupt the loader when powering on and pressing select (rather than start, which takes you to godmode9).
Can any one point me to a resource that would walk me through configuring a second emunand?
-thanks!
EmuNAND treats a separate partition on your SD card as if it were your NAND. In order to create this partition, you will have to re-format your SD card.
First make a NAND backup using GodMode9, just in case something goes wrong (later you're going to want to run a System Format on either your Sysnand or Emunand to "unlink" them. If something goes wrong, you're going to want this backup to get your stuff back). Then, copy all of the files from your SD card onto your computer.
Then throw it back in your 3DS and run GodMode9. Go to More -> SD format menu. In most cases, using the minimum size with Rednand should work fine (unless you're using a Gateway.) When it asks you if you want to copy sysnand, pick Yes.
Afterwards, you will need to copy the backup you made of your SD card earlier back onto the SD. Then your console will boot to Sysnand by default, but if you hold D-Pad UP while turning on the power it should load your Emunand instead (I'm assuming you're running Luma 3DS btw). Now the problem is that they're "linked", so so they're sharing the same "Nintendo 3DS" folder and will both have the same games. This isn't what you want, to unlink them you'll need to format one of them. You can use a homebrew software called TinyFormat to do this, pick whether you want to wipe your SysNand or EmuNand. Then boot into that one, run TinyFormat, and it will format your system without formatting your SD card (if you use the regular System Format in the System Options menu, it wipes your SD card, which you don't want to do!). After this, your SysNAND and EmuNAND will be unlinked, and you can install whatever games you want on either of them.
Important Notes:
- Unless things have changed and I am mistaken, GBA Virtual Console games on EmuNAND must also be installed on SysNAND to work properly.
- Whichever NAND you format using TinyFormat you will lose everything on. The latest version of Luma has Rosalina, which will let you get into the homebrew launcher, and then you can re-install FBI, FreeShop, and whatever else you need. If you're using an old version of Luma and don't want to upgrade, you can use GodMode9 to inject FBI.cia into your Health & Safety app, and install whatever you need using that afterwards.
- Having multiple NANDs allows you to go beyond the 300 game limit. You can have 300 games on SysNAND, and 300 games on EmuNAND. You can also set up more than one EmuNAND.