Here are some house rule for open table fantasy sandbox games.

Hanging around at the tavern

Player characters who don’t take part in an adventure, because their players couldn’t make it to the session, are supposed to hang around at the local tavern. It costs them 1 gp per day to stay there. This may well lead to going into depts, but that’s their problem.

Traveling

Player characters who need to travel quickly in order to catch up with a party may travel 18 to 90 miles or 3 to 15 hex per week. It costs them 15 gp for a week of traveling. Roll on the following table for each week traveling (i.e. if you need to travel 16 hexes, you need two weeks, so roll twice!). You gain the number cast on 2d6 times 20 XP per week!

2d6 event 2 you disappear and become a non-player character. Only the GM knows what happend. You might be found and become a player character again if the party successfully finds you. 3 Something bad happens. You’re traumatised and lose one level. 4 you’ve been assaulted and robbed. You reach your destination with nothing but rags (AC 9) and a cudgel (1d4). 5 you get injured and lose one week of traveling time – roll again. 6 you get help from some higher npc – you owe him a favour now. 7 you make an interesting discovery. You couldn’t gather much, but you’ve found (1) the entry to an unknown cave system, (2) ancient ruins, (3) the lair of a terrible monster, (4) a gate to another world. 8 you meet a traveling companion, roll again with +2. You get +2 on a reaction roll, if you want to hire him as a retainer. 9 you find some work on the way, and earn 3d10 gp 10 somehow you come in possession of a treasure map 11 you find a valuable gem (1d10*100 gp), lucky you 12 you find a magic item (GMs choice)

9 to 5 jobs for adventurers

Characters who stay at some place for a longer period of time might try to find work. Roll 2d6 plus charisma modifier. On a result of 8+ you find a job and earn 2d4 * 10 gp per week. If you miss you have to wait for a week and earn nothing. On a critival miss (2 on 2d6) wait two weeks before roling again.