I find it a bit weird to call these S60 games "unofficial N-Gage games", as they do not work from the N-Gage application or support any of the community features that separate N-Gage from regular S60 games.
Okay, here's our official explanation... 😊
On a technical level N-Gage games are effectively just Nokia-branded Symbian S60 3rd Edition games. S60 games can do everything that N-Gage games can do, because they're the same thing.
In effect, S60 games are unofficial N-Gage games.
S60 games can't access the N-Gage app's community features, but that's entirely a decision by Nokia to deliberately exclude them rather than a technical failing. It also makes very little difference on most games, for example there aren't really any community features on Dirk Dagger.
And S60 games can provide their own community features if necessary. TibiaME is a Massively Multiplayer Online game, and it can run online because the publishers use their own multiplayer servers, so they don't need access to Nokia's infrastructure.
The most accurate way of labelling these unofficial games would be Symbian S60 3rd Edition, but the trouble is that Nokia has avoided making them consumer brands: "symbian" and "s60" and "3rd Edition" don't really appear anywhere on the phone or its interface, and they're usually not mentioned in the publicity for these phones either. There isn't really any obvious way for an ordinary user to know what these terms mean.
Most Symbian S60 phone owners simply don't know they own a Symbian S60 phone, whereas people who own an N-Gage-compatible phone may well know about it because the N-Gage app comes with their phone's firmware (or it will do soon) and appears as an icon on their main menu. It also seems likely that by 2009 Nokia will include the N-Gage application on all new S60 devices, which means that N-Gage-compatible and S60-compatible will be one and the same thing.
Because of this situation, we decided to call them "unofficial N-gage games" instead of "symbian s60 games", because N-Gage is a brand consumers might know about while Symbian and S60 aren't.
they are pretty much as unofficial "N-Gage games" as any other mobile game out there.
That's not quite true.
N-Gage/S60 games are native applications, so they can access the phone's hardware directly and use it to its fullest. There are some things native apps can do which non-native apps cannot do.
Java J2ME and Flash Lite games are non-native applications, so they cannot access the phone's hardware as directly, which restricts what they can do on the phone.
Obviously if a game is something as simple as Tetris the user is unlikely to notice what platform it's on, but there are some games where the differences between platforms become much more obvious, and that's why it's important to make a distinction between them.