>>725503207
Have the same continue until all characters are downed. The requirements for every job get harder and harder, but take a minor break when you lose someone.
You can still level them up as needed, but there's a soft max level for people, so you need more and more exp before it becomes unlikely to level up in any decent time.
The city has its own "health bar" that is increased or decreased with call successes and fails.
Every now and then you get a hero training session or expendable items.
There's a leaderboard, and succeeding in calls with lower percentage chance gives a massive boon, leading many people to risk it all.