Either use install a Virtual Machine program with Windows on it or dual-boot into Windows. You can't natively run Maplestory on Ubuntu.[/quote]
Yes it can be run on Ubuntu. Also, using a Virtual Machine would cause him massive lag, asides that his connection might not work properly. You'd needa bridge the connection from Ubuntu to the virtual machine, if using VMWare. I read somewhere on a forum that you need a load of scripts and stuff to run Maple on Ubuntu, but it can be done. There was a video proof in there too. Try google, your best friend for this.
VMWare is a pretty good software for running virtual machines, but it get's really laggy. I guess it depends on your hardware. Why not install it as a dual operating system so you can select which OS to start when you boot the computer? It'd save you from tons of lag.