Why do computers with this hardware run games so well?

[Sukhoikip]

When i was at my local library, out of curiosity, i decided to check how well the computers (Dell Optiplex 380s) handled some basic games. To my amazement, they ran all the 3D games I confronted them with (such as Minecraft and the first Halo) remarkably fluidly. After finding this out, I double checked the specs. The processors are merely Pentium E6300s (i think), with GMA X4500 graphics, 4GB RAM and running Window 7 Enterprise. I know in an objective sense this is meh performance, but with those specs it seems miraculous. Anyone have a clue how this performance is being reached?
Dell's full specs are here

http://www.dell.com/support/home/us/en/04/product-support/product/optiplex-380/manuals

 

[Mr5oh]

Those aren't exactly demanding games? Most cell phone hardware would be enough to run those fluidly these days. 3D games have been around forever, running on much less powerful hardware.

 

[Shadowex99]

Yea, My School's computer are like the same thing and can run minecraft on normal at 60 fps. I was just fooling around and managed to discover this minecraft loophole (use a usb and you can easily get into a computer that doesnt allow games).

Edit: Pretty sure they are Dell Optiplex's too.

 

[Sukhoikip]

Those aren't exactly demanding games? Most cell phone hardware would be enough to run those fluidly these days. 3D games have been around forever, running on much less powerful hardware.

yeah, but newer ones at my school have far better hardware and dont run those games as well