Alpine hikes are 2 500 / 3 000 meters high' hikes. They are more exposed and difficult that our 1/2 day or day hikes. You'll usually need a rope and an harness (no need to have it, your guide will give it to you).
They are quite a few great alpine hikes around Megeve: the Aiguille de Warens in the Fiz massif, the Pointe Percée in the Aravis massif, the Mont Charvin in the Aravis massif.
If you are sporty, try it - you'll love it!