The basic principle of Triple Town is nice, you have a limited area and have to put three objects of the same kind next to each other to create a single upgraded version of those objects, that can again be upgraded by putting two more objects of the same type next to it - and so on. This can become quite tricky the more items you have on a map since once you run out of space to place objects the level is over. When you upgrade an object you get points for it, naturally the more advanced an upgrade is, the more points you get. You can use those points to upgrade your town, which is the hub from where you access the randomly generated levels. The town's buildings generate items that will help you during the regular levels. The bigger and better your town becomes, the more and better items you will get.
The problem with the game is that there is no goal. No special challenges, nothing to achieve other than endlessly upgrading your town. It's the same thing over and over, and that felt rather pointless to me. You could try to get the best possible upgrade of an object (there is even a Steam achievement for it), but for that you need a lot of special items, and you can only obtain those by upgrading your town and collecting more money. That means you need to grind for dozens, if not hundreds of hours and all you get for it is a Steam achievement.
Imo this would be a decent time killer for mobile platforms, but there are simply far better puzzle games on PC to waste your time with Triple Town.