The Escape Encounter

A common problem with Open Table or West Marches style play is that each session needs to end in a safe "base" so any new combination of players (and therefore PCs) can venture out together in the next session with no continuity errors. But if part of the game is navigating a dungeon or wilderness, the PCs need to leave themselves enough time to do so and that's hard to estimate if there's a risk of random encounters or getting lost. We also don't want to overly trivialize this travel. So what options are there?

1. Trivialize the Travel

You don't want to. But you could. If they're not in the middle of an encounter, this is the simplest option.

2. Escape the Dungeon Table

You could roll on a table to determine the fate of the party. The Alexandrian has a good post on this.

3. Escape the Dungeon Encounter

What if, in the event that the PCs are not already safely back in town near the end of the session, the DM mandates that there will be one final random encounter? Leave enough time to resolve that encounter - probably 30 minutes in newer editions, less in OSR or pre-3rd Edition games. Then do the following:

1. Roll on the Random Encounter table. If there are multiple routes back to town, perhaps the PC's choice of route affects what table is rolled on or what encounters are possible.
2. The DM places the encounter anywhere that makes sense on the chosen route - probably a choke point that requires the PCs to sneak past, or fight past and then retreat. This encounter should be basically impossible to avoid. (If there was a room that had some neat terrain features or a trap that went undiscovered, that's great. If the DM chooses to place the encounter in the wilderness, be sure to factor in any mounts, wagons, and hirelings left outside the dungeon.)
3. Set up and resolve the encounter as normal.
4. Once the PCs have snuck past, spoken peaceably with, bribed, fled, or killed the monster(s), whoever escapes automatically arrives safely back in town with whatever treasure and XP they brought with them.

There's a ton of reasons why this would be awesome.

1. End the session on an intense high-note. Great climax.
2. Speed and stealth become super important. Do the PCs risk taking off heavy armor? What type of mounts/wagons/hirelings did they bring?
3. It's an encounter where the default goal is not kill the monster and take its treasure. In fact, as it's a wandering monster, it shouldn't have any treasure.
4. If you can talk or bribe your way past the monster, high-charisma PCs and having treasure is super important.
5. If you have to fight, Morale becomes super important. You may not need to kill them, just scare them off. Undead, oozes, and constructs become really scary.
6. If you can't scare them off, positioning becomes super important. Charge through, use crowd control Spells, and execute that Fighting Retreat (a rule that affected attacks and AC in older editions).
7. Once you have an opening, flee! Use chase rules if your system has them. For once your speed matters and fast monsters are really scary. You might have to drop treasure, caltrops, flaming oil, or equipment to lighten the load!
8. Getting lost matters. Idk - I'm just making shit up now but perhaps if you're lost before the encounter or somehow get lost fleeing from the encounter something else bad happens!
9. If an ally goes down or gets stuck behind enemy lines - will you really stay and fight to the death?

All. Good. Shit.