tap on start then chapter 1 to get started and i think you know the rest. (sometimes when opening capsules, the unit you got doesn't show)
this game was a long time awaited for me and (maybe) many others, this is similar to the original tower rush besides 3 main differences. One, we can finally have more than one unit! Two, there is a unit capsule where you can get units that are unavailable in the campaign, and three, the campaign is designed much differently.