A free app for Android, by djdron.
Spectaculator is an unofficial emulator for the Sinclair ZX Spectrum, the most popular home computer of the 1980s. It emulates the hardware and software of the original machine, and allows you to play many of the most popular games, including the official ones.
With the latest version of Spectaculator, you can enjoy the same experience as you had in the 1980s, with a modern look and feel. The interface is similar to the one used in the original machine, and it is easy to use and understand.
This unofficial app is based on the open source project, and it is free to download and use.