Too much walking around, not enough... anything else. Seriously, how do you do anything other than walk around and talk to people?
If I recall correctly, you can also walk into monsters spread around the game’s various maps. This changes the gameplay up by introducing a turn-based battle system, in which you and a foe exchange in combat, where you pit your skills (earned through quests, exploration, and further battle) against one another to earn various rewards. Losing (or surrendering) to these enemies will trigger an alternative and unique bad ending, based on the enemy you lost to. However, you are prohibited from viewing them unless you are over 18 years of age. I hope that helps answer your question.