With that information in mind, you could write: "Ich mag Sport und gehe gern zu offenen Treffs, wo man ohne Anmeldung oder Mitgliedschaft mitspielen kann." It is very long, but than everybody knows what you mean :-)

Oh, thank you! That helps quite a bit!

In German there isn't yet an equivalent expression for this (according to Google), but when it's something new I'm sure in a short time it will be 'Pickup-Spiel / Pickup-Game' in German :)

Was trying to talk about pick up sports - where the teams aren't preformed and individuals show up and play with whoever is there.

What do you mean with "und ich spiele aufnehmen"?