Nighty Knight: Frontier War TD

This is a midcore tower defense game played solo, likely in portrait mode, that offers a unique take on the genre with balanced progression and merge mechanics. While sessions can be medium-length and the game is playable without sound, its monetization is considered expensive and potentially pay-to-win, and it requires an internet connection. It's best suited for players who enjoy strategic depth and are willing to invest in its premium-priced content.