This is a game that wasn't love at first sight. In fact, maybe you even disliked it at first. However, over several playthroughs you began to appreciate its qualities until everything clicked and you realized what a gem it was afterall.
That game for me was Sub Terrania. When I first played it the controls were not intuitive and the mission based objectives were frustrating. However, once I overcame the learning curve for the controls and mission based objectives, the game really came together in a big way to deliver an awesome gameplay experience. Everything about this game rocks, the graphics, soundtrack, the combat, the exploration and sense of urgency really make this one of the best gameplay experiences on the Genesis for me.