I still play even if 2+ can’t make it. It will depend on your group but my group of 6 has 2 very flaky players.

The problem only happens when a group feels they need to delay if someone can’t make it. As a GM I have a set day/time and play without the missing players.

The first system I played was the D&D Next playtest but the first rpg product I bought was the Shadowrun 5e corerulebook. I never actually played it and it seems too complicated for my tastes now but I still have the book.

3:16 and Mothership as a Gm. Always eager to try whatever else people in my group want to run.

If you’re running a sandbox, you just need to review a bit ahead of the party in the various dungeons.

DCC funnel adventures are really great. I’m not a huge fan of the system beyond that but lvl-0 adventures make a great 1-shot.