Have you ever wondered how many, for example, Commodore 64s it would take to equal the processing power in your current PC? This site might not really answer that, but it does show that your machine can easily duplicate all the old 8-bit computers from Commodore, Sinclair, Acorn, and others. By our count, there are 86 emulators on the page, although many of those are a host machine running a particular application such as Forth or Digger.
If you are in the US, you might not recognize all the references to the KC85, this was an East German computer based on a Z80 clone. Very few of these were apparently available for personal purchase, but they were very popular in schools and industry. These were made by Robotron, and there are some other Robotron models on the page, too.
If you aren’t interested in period games, there is still Forth, Basic, and even assembler for several of the machines. The emulation isn’t very snappy but probably is still faster than the real things. If you get stuck, it might pay to know that the Esc key is mapped to the break key.
Speaking of keyboards, the KC85 was notorious for having a very cheaply made “chiclet” keyboard. So using one with your full PC mechanical gaming keyboard feels like cheating. Of course, you don’t need a full PC to emulate an old computer. We’ve even seen the Commodore and the PC XT emulated on the ubiquitous ESP8266.