Not a fan of installing apps. Personal peeve.

At a high level, why do you like Arknights?

I like the art and storytelling -- the characters are somewhere between unbearably cute and tough special forces lifestyle. It fits my kemo lifestyle [1]

I like the tower defense genre in general, there is a lot of depth to the mechanics, and many of the levels are challenging. It is a gacha game but it's fun to play if you don't spend any money or if you just get the $5 monthly card which I think is fair for the entertainment I get compared to other games. Unlike other gacha games (say Azur Lane) it doesn't try to take over your life with notifications and the UI is refined [2] Unlike, say, Genshin Impact, download sizes are reasonable.

[1] https://mastodon.social/@UP8/tagged/kemolife

[2] ... not like FGO or those games where you collect clothes other than Love Nikki