As one of those people who can’t seem to put the game down, I would like to suggest a mini-game be added. The game (while giving no or very minimal rewards) could be played while simultaneously waitng for your heroes to regenerate. I propose randomly generated opponents leveled to match your chosen team.
Boosts would be disabled, team-ups randomly generated.
Each match begins with the chosen characters from the player’s roster at full health and at their current levels. The matches would have no impact on your game progress our character health.
Love the game despite some issues. But it’s a total bummer when I’m in the mood for a match but all my guys are recovering for the next series of battles.
many have suggested this many times. basically a shield sim, 3 randoms vs 3 randoms..
easy - 1/2 the rewards from a standard shield sim reward
medium - same possible rewards from a shield sim reward
hard - slightly higher rewards than a shield sim reward.
so, for like now, when we are at work, with nothing to do, carnage having eaten most of our roster alive, and waiting on health packs.. we could grind some iso or bagman covers, maybe a token or heroic token or 2.
had an idea a while back about solo missions. where a character went to investigate a rumor of ISO stash or other reward. it would be either a goon node or 1v1 fight. once a hero was sent out and completed the mission they were removed from the pool of candidates for other rumors. it could be limited by a daily total amount, certain rewards for certain 
levels, or limited only by your roster.
How about an infinite wave mini-game of every single toon in MPQ? They get harder after every 5-10 waves. No significant rewards (maybe 20 iso per match won) but awesome bragging rights to your friends (“Hey guys I’ve hit wave 1337 in the infinite waves mini-game! Betcha can’t go as high as I do! Herp Derp.”)
Just to kill time, ya know?