it's a pretty fun time-killer, since it's available offline as well. i have been playing for 3 days and I have yet to get a 4* character, solo pulls do better than multi tbh (multi either gives you shit tons of 2* dupes or just a plethora of 1* with no signs of 3*) so gacha rates are pretty bad. I use a maximum of 6-8 workers in my office, exceeding that number is really hard to manage since the controls are rather unrensponsive despite the boss upgrades (punishment control is broken). grinding coins is the worst part of this game, literally most upgrades cost 10k up on most items and levels just give you 300 each, leveling up 10k and the mining thingo only giving you coins depending on your rank. diamonds are no problem, they're pretty reasonable. it's still fun and challenging though, having to make the player utilize worker fever skills.
oh and elly is a free character once you clear her event, gilbert however (and most 4* characters) is a top-up character. H A V E F U N ･ิ≖ ω ≖･