As far as I know, you can use any 3DS game's header.
I tried a non-online game's header on an online game but was unable to connect. I believe headers should come from a game that is capable of going online. However, I only tried my Cubic Ninja header dump with SSB vs my Street Fighter IV header dump with SSB. Every game that I have that plays online has worked with my private Street Fighter IV header. I used Gateway Rom Patcher to fix the chip ID and manufacturer as necessary for each online game.
The .3dz extension is only for Gateway to enable online play. It shouldn't matter if it's a .3ds or .3dz extension before going to Gateway. I can successfully go online with my private Street Fighter IV header. I will see about trying some of my other headers to see if it matters whether the game supports online or not.
EDIT: It should also be noted that some games appear to use the Nintendo Network while others use their own servers (FIFA 14 and FIFA 15 for example for downloading new rosters).
Ok, I can confirm that using my Pilot Wings Resort private header with a modified chip ID on my eShop dumped Mario Kart 7 rom works. It doesn't appear to have any kind of connection to whether the game is online capable or not. The eShop dump of my Mario Kart 7 rom didn't have a header to begin with since I purchased it on the eShop and it was essentially a CIA install prior to doing a .3DZ conversion for playing on my Gateway red card.
Back on the older header guide, it was said that Zelda A Link Between Worlds header worked.
If this was the case of offline game headers working for online games, then I think he best headers to use are from offline games. Then you don't have to worry about anyone going on line with it.
I feel like buying a used game from Gamestop then returning it. There's no chance another Gateway user will use that same exact copy of the game for their header.
Back on the older header guide, it was said that Zelda A Link Between Worlds header worked.
If this was the case of offline game headers working for online games, then I think he best headers to use are from offline games. Then you don't have to worry about anyone going on line with it.
I feel like buying a used game from Gamestop then returning it. There's no chance another Gateway user will use that same exact copy of the game for their header.
Just buy a cheap new game. I'm sure you can find one under 20.
This^
Buy it and keep it.
I bought Resident Evil: The Mercenaries 3D for just under £4 ($6.10) from Amazon (new).
Having a quick look at the US site:
Crosswords PLUS $5.49 [offline]
Pro Evolution Soccer 2013 $6.84 [online]
This^
Buy it and keep it.
I bought Resident Evil: The Mercenaries 3D for just under £4 ($6.10) from Amazon (new).
Having a quick look at the US site:
Crosswords PLUS $5.49 [offline]
Pro Evolution Soccer 2013 $6.84 [online]