Buy see also Accept : to receive willingly
You "willingly" ,according to you "because it was there", played HL2.
LOL! Wow, you are not only ignorant of English but apparently desperate. "Buy into" is a vernacular expression which means to believe or come to believe as I previously stated. I did not buy Half-Life 2 nor did I buy into the hype that it was great. I didn't think it would be better than games I had previously played, and based upon what I saw, it wasn't.
Now, as for your cited definition of "buy", an example sentence would be "I don't buy that explanation." meaning "I don't accept that explanation as valid." And, yours isn't.
This comment was edited on Sep 13, 13:32.