Is Ubisoft ripping us off?

I've now seen Splinter Cell 5: Conviction and Assassin's Creed and except for different time eras, the game are starting to look kinda similiar. I'm gonna buy both of them regardless, but does anyone else think this.

Similarities:

Social Stealth(hide in crowds of people to blend in)

Defensive Gameplay(More focused on escaping your enemies than fighting them)

Ability to hide in different objects(Like under a desk or in a wagon of hay)

Focuses on melee combat more than long range weapons(AC has you using a sword, SC5 has you using what ever you can find)

By the same token, you got ripped off when you bought Halo 2 after getting Halo. Almost all the same weapons, gameplay mechanics, etc.

No,they're going to have completely different stories and missions, plus SP5 has guns and AC has the crazy acrobatics. Saying Ubi is ripping us off is like saying anyone who's ever made a sequel has been ripping us off.

Well it's probably the same engine and yeah it's kinda similar gameplay. But that's not a rip off at all because the games are vastly different. But Nintendo on the otherhand.... there's your rip-off right there.Lazy_Boy88