Shining Force: The Sword of Hajya.
My aunt bought my bro and I a Sega Game Gear on our trip to the US in ‘95 or so. We got this game and a Tetris-like game called ‘Gems’ or something. This mofo drained six AA batteries in no time! It didn’t help that I didn’t understand the spell ‘Egress’, which would allow you to retreat whilst still gaining experience. So I’d get to a certain point in the game where my lack of experience points would catch up, and I’d be at a dead end.