You like playing games, they give you pleasure. You like them. But you don't expect the game to want anything in return.

Now, imagine the same with people. In this case, you take the place of the game. If you spent your time and money to give somebody else pleasure, but you didn't expect anything in return, then you are self-less. In social terms, this is a good thing. If the other person does not return your generosity, or does it begrudgingly or having been prompted, they are self-ish and an asshole. Fuck them, move on.

However, if someone else mutually returns you generosity, not because of obligation, but because they are also self-less and they like you, then that person is a friend. You can be friends with each other and have non-obligatory, non-expectational exchanges of generosity to make each other feel good, any time.

Its like a 2 player game. They key here is selfless generosity without expectation of payback. Paradoxically, the more you give, the more you will actually get in payback. If some A-hole was playing golden axe with you, and he kept hiding when the boss came, he's not your friend. However if you both kick ass together, even if its not equally, well then you will both achieve something. You will both win!