Good offline no internet needed to activate games

so i need a couple of games to show off our cool gaming pc prowess in an event where our wifi sharing cellphones cant even get a signal to authenticate with steam or origin. i need a couple of games i can put on a usb drive and install them on these pcs. any suggestions? thanks


Anything from gog?

The Wticher 3

also steam does games offline..

Oh never mind, you want free games I assume?

Any boxed game with a key would work

no, i could pay for them, i dont mind. i know some steam games go offline, its that they need to authenticate at least, and i have no internet waht so ever inside the convention center.
i need to be able to download them at home tonight and then bring them tomorrow on a usb drive, if they have an offline key, thats ok too. i will try to find witcher 3 on gog and xonotic (somebody mentioned it, it will be good to try). any other suggestions are welcomed

Lichdom: Battlemage is a pretty good one, available on GoG too

just about any pc game made pre 2007 will work.then you have indie games made with rpg maker and almost any console games nintendo wii or older excluding the original xbox.