If you choose N-Gage (device), you'll find a page about games designed for play on the Nokia phone/handheld console hybrid called N-Gage. You can buy most of them on MMC card (today, most likely found online on eBay) or download them online at https://www.emuparadise.me/Nokia_N-Gage_ROMs/List-All-Titles/17 for individual games and https://www.emuparadise.me/Complete_ROM_Sets_(Full_Sets_in_One_File)_ROMs/Nokia_N-Gage/96370 for a set of at least most N-Gage (device) games.
If you choose N-Gage (service), you'll find a page about games for play on the Nokia mobile gaming service for various Nokia-made S60 Symbian phones called N-Gage. To find out how to install N-Gage (service) games on your N-Gage (service) compatible device, as well as the software you need to run such games, you can go to https://www.youtube.com/watch?v=znFneIM5RT4.