Can you play PC Rom games without internet connection?

[Jay]

Yes you can. If the game is not on steam or has RMD(Anti piracy measure) mostc games have RMD or are only obtainable from online services like steam. If the game was originally from a disc, you can mount the iso(virtual copy of the disc) onto your computer using a virtual cd drive. Basically, it will trick the computer into thinking it has a cd drive when infect it's a fake cd drive loading the iso as if it was a real disc. that's as far as I can go without breaking the rules.

If the game doesn't need online to play(not online game like campaign mode in most games then it's okay. Some games like diabolo allow you to play in LAN(local area network). Basically, it allows you to play with the computers who are playing the same game and connected to the same router you.

Hope that was in-depth.