You play as a service worker on a train.
Each level has a pre-set length, but there's an advanced mode that adds delays. Each level has a full background scenery generated, but it's just one long 2-D scroll in the background.
Gameplay consists of responding to various requests and occasional periods where it gets hectic or boring.
You can save+quit mid level, of course, but you can't go back to previous saves - if you screw up, you have to wait out the rest of the train ride.
Grading ala DDR: you get points for responding to points promptly, fewer points if you miss the timing window, and a penalty if you don't respond in time. If your score goes too low, you're "fired", and it rewinds to before you committed to this departure (a game that demands hours cannot have perma-death, I think)
Standard incremental roguelike: each route pays an hourly wage based on the difficulty, as long as you don't get fired. Use that money to upgrade your apartment / lifestyle between runs - this could potentially include actual upgrades (sneakers give you more endurance, etc.) or be purely cosmetic.
I figure that if you're spend 3 hours traveling, it needs to be a game where the actual gameplay takes place *on* the train, while still keeping the background in view and fitting in well with real-time gameplay (that way it really does take 2 hours to finish a 2 hour train ride)
If you wanted to make the travel more important, perhaps the character is trying to collect various items from each city, which requires both reaching that city and having enough money? A sports jersery from every major team, or some unique signature item.
Probably also some bonus for when you get to rest in your apartment -vs- having to stay at a hotel or take another train back.
You could probably generate the map based off real train schedules, so if you arrive at 2 PM (based on your computer's actual clock), that affects what other routes are available (do you want to take the less-profitable 3 PM, or wait two unpaid hours for the 5 PM?). Probably with some fake extended routes for night owls - maybe mirror 7 AM - 7 PM to cover the other 12 hours. I'm sure there's creative solutions. Or you could just make up your own randomly generated time tables and have different seeds.
Scenery would be a bit harder depending on exactly how accurate you want it to be - I think capturing the right mood at Minecraft resolution is something you could do automatically off Google Maps data. But that's definitely going to be a huge art-sink on your art budget if you want anything bespoke.
Game play can presumably be fairly procedural - the main thing is remaining focused and prioritizing/remembering multiple tasks. I'd probably avoid the common "quest log" except as an Advanced Mode for accessibility. Someone wants tea, you have to turn on the kettle, wait two minutes, pour the tea, and get penalized if you forgot to let it sit for a minute to take the edge off the temperature.
Expansions can also add various new activities on the train - juggle drink orders, a hot grill, and all of your assigned janitorial duties for that true service work feel >.>
