Is there any good reasons to use one over the other? And are there are real time samples (like 2 player pong) that could help me understand the very basics?
check the asset store, there are several fully working photon examples
Is there information as why someone would choose Photon over the built in networking ? Is it because PHoton provides a free server (I think?) and maybe Unity networking does not ?
Which one is good for online games such as Counter-Strike or call of duty or …?