This is a tower defence game that allows you to build up your home, and turn it into a fortification for some epic-looking massive battles.
During every level you have a local progression: building walls for those mindless monsters to wander through, placing and upgrading turrets, and selecting from a random set of boosts to give each play a unique flavour. You can't delete or sell whatever you build, only upgrade the basic turret into other turret models through the progression branches. The gameplay is very focused on that killzone building puzzle, with no micromanagement distractions.
The puzzle though will rely more on intuitive understanding rather than numbers, as there are none, aside from prices. As enemies don't become stronger, but rather the difficulty increases with their quantity, the player can reliably discern the effectiveness of his strategy by the rate by which the orcs turn to giblets.
There is also a macro progression - between levels, you unlock and select from a set of artefacts to "wear". They are not straight power increases, as you start the game with some of the most powerful ones - the armour artefacts, which allow your Home to take more hits. All other artefacts can provide circumstantial opportunities but don't yield protection, leaving you more vulnerable, thus requiring a more intricate strategy overall to harvest their benefits.
The other aspect of gameplay is idle gardening. It is up to a player to decide when to stop planting seeds, and collecting crops and instead, turn your house into a fortress, Home Alone style.
It is important to nail that farming/slaying orcs balance. There should always be something worth fighting for, a peaceful life waiting when all is done and the dust settles. The player is very much encouraged to take breaks from slaying waves of invaders, watering the plants, and return to real life, as the farm will keep producing while the player is offline. Giving that casual mobile game experience that makes you feel effective while not actually doing anything.
Despite the causality, the game doesn't dangle any carrots and unfulfillable promises in front of the gamer, instead, it is the carrot you planted yourself that needs protection - and that is your motivation to stay in the world of Savage Turret long enough to complete all of the levels.