iMac good for ROBLOX,Minecraft ?

[NoobsUseWindows]

I plan on getting the newest iMac but i am worried, i am a daily gamer and i really want to be satisfied that i will be able to play sand-box games better than my current computer (Windows 8 HP) i also play a lot of laggy games such as space engineers will the iMac do it without lag?

 

[tillsbury]

Minecraft at 5k:

https://www.youtube.com/watch?v=Ajd7lL9qSis

In another related video he shows that it's running at around 120fps.

(note: the video above is screen captured and so not that quick)