Play Mega Man Ultra on NES - Emulator Online.
Beginning of a dialog window, including tabbed navigation to register an account or sign in to an existing account. Both registration and sign in support using Google and Facebook.
The Lightbots are definitely my favorite robot masters, though I'm only following one person who draws Megaman stuff with any frequency right now, which is why there's so much Gemini and Charge in here. Said person has kinda skewed the character ratio of my favorites.