I remember about 13 years ago I had a handheld system known as the Gameboy advance. I would spend my time playing strategy games like Pokemon all day long, then a game series known as fire emblem came into my life. The layout is almost like a checkered chess board with the black and white squares being replaced with an outdoor terrain.
You move each of your "chess pieces" once every turn and attack the enemy army. The terrain can be used to your advantage as higher ground will help your archers and what not. Now the twist on this simple strategy game is that your decisions last until the end of the story. If one of your characters die they are gone for the entirety of the game and can not be retrieved afterwards. This can make certain levels quite intense and also more rewarding.
Each unit in your army can also be leveled up and sort of evolved after a set amount of levels into a killing machine. When Fire Emblem came into my life I started putting Pokemon down and went to war.