It is some years since I tried the QSOnet and Hamspherevirtual amateur radio systems. These are virtual representations of the amateur radio bands running on a PC based "virtual transceiver" allowing very real simulations of HF operating with the ability to tune around and "work" real people just as one would using an HF transceiver and the ionosphere.
Arguably they are a useful training ground for real HF operating. For some people without access to external antennas, they can provide a ham radio experience without the problems of TVI and the costs of a real radio. This is NOT true amateur radio, but I have some sympathy with those who enjoy virtual amateur radio for the pure fun of using it or where circumstances prevent real operating. The Hamsphere system has a very neat "transceiver" for both iOS and Android devices in addition to a PC version.