TLDR: It's an exceptionally engaging idle/clicker game but it also carries with it all the psychological warfare most of the genre does.

This is an idle/clicker game. You mix waiting (either online or with the game closed) with periods of activity. Your goal is to lead a group of wacky adventurers through their wacky adventures.

The good:

There is a degree of strategy involved here I've rarely seen in most games in the genre. Each run gives you a formation and possibly other conditions (like influencing prices of all units, disabling passive DPS, or putting a suicide bomber at the head of your formation that will make you lose that area if he dies). You need to figure how to place your characters to achieve victory. And placement does indeed matter.

There's a lot of systems at play here. You can send them on missions forcing you to rethink you formation for a while. Getting them permanent EXP or just EXP for that run (so you do start doing runs faster and can progress a bit further every time). There's collectible gear, runes, taskmasters, events... a lot of things. And it all works mechanically rather well and doesn't seem to contain any major bugs. When you complete your objective you restart the run, choose a new objective, and become stronger and stronger.

The bad:

And it's all a trap. With "traditional" game pricing model you buy the thing and you for all purposes own the thing. Steam and other digital stores are wagging their finger at the word "own" but hey. Some developers choose then sustain themselves through DLC, season passes, merchandise, possibly Patreon or stuff. This one goes for "micro"transactions.

Almost every single system or a mechanic can be skipped, accelerated, tweaked, or made more convenient with buying specific packs or with premium currencies. You are constantly bombarded by ads and the store is by far the most complex interface in the game. Of course, there is no hard limit at how much you could spend but even going for the one-time packs like characters it could be hundreds of dollars I think. Every single mechanic is designed to hook you in but also dangle more stuff in front of you.

While there is a strategic aspect to this game and you juggle dozens of considerations and that is enjoyable unless you enjoy the game as it is and don't intend to buy or buy at a determined value to support the devs... if there's even an iota of you with addictive tendencies or you are annoyed with waiting and endless resetting... just go play something else. It won't be good for you.

All the other aspects of the game are shadowed by the monetisation. Mission, item, and character descriptions are usually one to two sentence blurbs which are mostly references to other IPs, subversions of conventions in fiction, or playing with words. I am trying to say there are some other things but they are miniscule compared to the waiting/baiting aspect.

"But that's basically every game in the genre! Is it fair to criticise this one?" Yes. And yes. That doesn't make it any better. I prefer my games not to be designed from the first line of code to the very last to bait me into spending an indeterminate amount of money.