The games that are built in Unity some of them don't fully load, and stuck somewhere near to the end:

I really wanted to play a lot of games, but I think I might facing this issue because something I am missing, anyone is facing the same issue?

i have the same issue ,  some games load and some don't

Same issue.

Maybe browser issue ?

(Slime color , one life one chance  , mecontrote , the last pizza  ,  انقذ الزهره  , قاتل المافيه  , Kill the zombies ) هذه  الالعاب تحدث بيهه هذه المشكله 

جربتهن اكثر من مره وتركتهن على اللودنك مده طويله ونفس الشي وجربتهن على متصفح الفاير فوكس  ونفس الشي للاسف 

راح ارجع احاول اكثر من مره حتى اتاكد ليس مني المشكله 

I think that Unity 2020 have problem in web game that must be fixed by player settings it happened with me but i fixed it 

yes you are right it happend to me as well in unity 2020  the solution is:

go to File > Build Settings > Switch to Web > Player Settings > Compression Format > Select Disabled  

and thats it  but you cant upload it to the game right now speak to the admins so they give  you a chance 

happens to me as well, seem its common problem.