The cheapest graphics card you can play it on is an NVIDIA GeForce 8600 GT. Shadow Bug system requirements state that you will need at least 4 GB of RAM. To play Shadow Bug you will need a minimum CPU equivalent to an Intel Core 2 Duo E4700. You will need at least 675 MB of free disk space to install Shadow Bug.
Shadow Bug will run on PC system with Windows 7 and upwards. Additionally it has a Mac version.