You missed a few "&" characters. Try this:
"gameid=" & Game_ID & "&roundid=" & Round_ID & "&score=" & Score
I'm not sure about the access token. If it needs to be sent in the same request then yes, you need to add it to the string.
Did you check error messages in the console log? The problem may be with something else, for example it could be CORS issue because you are using http protocol.