Congratulations on discovering that there is far more in the game to just decending downwards. Reaching the boss at the bottom of the dungeon is just a tiny fraction of the things to discover and do in this game. From bonus bosses like the two you just discovered in the pyamid and beyond the volcano, to secret questlines with interesting rewards for completing them. Good luck in your exploration. There is so much more to discover.
Damn, this video made me nostalic. Feels exactly like when I bought the game and some hours in realized that there is more to discover than going down. Now im here with almost 400hrs playtime. Happy Noiting! :)