Tank Battalion (1980): Yet another Namco game to be overshadowed by Pac-Man, Just like Rally-X (Not exactly) and King & Balloon. But unlike all three, it runs on the lowest hardware 1× MOS 6502 1 Mhz (The only Namco game with this hardware, their first game- GeeBee ran on superiour hardware) so controls were unsmooth and characters were passing tons of pixels each time they move. Gameplay is simple but fun- You are a tank, who needs to destroy 20 enemys and protect your HeadQuaters (Eagle on the map) In each level. No powerups, only one landscape type, only 8 different levels- nothing unusual.
Unlike mentioned before games, Tank Battalion got MSX port with improved controls and powerups system and awesome Japan-only NES improovement-port titled Battle City (1985). It featured 5 landscapes, 6 powerups, 4 enemy types, 35 levels with some of them being Mappy or Dig Dug references, multiplayer at the same time (Original allowed to play only by turns) and freaking level constructor. Even if it was success in Japan and "Famiclone" countries, I have never seen many people taliking about it. And thats a shame.
Then Tank Force came out in 1991, and man thats cool. Even more enemys, even more powerups, 2-4 players at the same time, Pac-man reference on Level 17 and Boss Fights. To tell you how much its underrated, not even people from "Famiclone" countries, where Battle City was success, knew this game exists untill 2016 and 2017 when its finaly included in latest "Namco Museum" for Switch. Maybe that one is overpriced, but for me- Its worth it!
There also were Tank Battalion Blitz(2012) and Battle City: Operaton Dengeki Offline (2017) for Ios and Android, but first pulled out from App Stores in 2015 with second one being Playble in Japan only. Namco pls