If it's an A500 I'll bet it's got 1Mb RAM.
512kb chip RAM and a 512kb fakefast RAM (Minimem was most common here in DK) upgrade fitted inside the trapdoor expansion slot on the bottom side of the Amiga.
If you're lucky it's a Maximem with a total of 2.3Mb.
You need a joystick for sure, there's not alot of Amiga games you can control using the keyboard.