At the end of the day anything that runs on Linux without needing additional compatibility tools is native.
You could make a distinction for Windows/whatever games bundled together without Wine/eON/whatever and depending what want to determine that might make sense but at that point you probably also want to exclude things like Unity that don't really do a great job at integreating into the Linux environment.
SDL can be used for porting games (ie, making them native) and that's what it was originally created for but it's not really comparable to bundling a Windows .exe with Wine, which would add a lot more complexity.
You could make a distinction for Windows/whatever games bundled together without Wine/eON/whatever and depending what want to determine that might make sense but at that point you probably also want to exclude things like Unity that don't really do a great job at integreating into the Linux environment.
SDL can be used for porting games (ie, making them native) and that's what it was originally created for but it's not really comparable to bundling a Windows .exe with Wine, which would add a lot more complexity.