Can I add additional games to the Magnum Monolith?: Absolutely.  The custom menu software that comes with each Magnum Monolith easily allows additional games and programs to be installed and used with the Magnum Monolith -- integrating them seamlessly with the joystick/trackball driven menu system. 

Are the games on the Magnum Monolith exactly like the originals?: Yes, they are.  The Magnum Monolith uses emulation software to emulate the arcade games perfectly.  What this means is that rather than being a rewrite of the game for a different platform (that is a new program being written to act something like the arcade game -- like many home versions of arcade games for various game consoles) it is instead using the PC inside the Magnum Monolith to act like the chips present in the original arcade machine (which can vary greatly as most arcade machines were custom designed for the particular game that they played).  Because the PC is acting like the chips of the original arcade machine, it is running the exact program code of the original arcade game.  Every tiny detail, even the idiosyncasies like kill screens, is present.