MIDI has been one of the best inventions of the past decades in terms of music composing, because it is now possible to transmit data related to musical notation (up to 16 multi-timbral channels simultaneously) through a single cable, making the composition of any song a lot easier.
Put a virtual piano on your MIDI devices
Together with this system, various companies launched a series of controller keyboards that allowed the user to use sounds from any sound module or computer, one of these virtual modules was Virtual Piano. This small application virtualizes all the instruments included in any General MIDI module, so we'll have any kind of strings, pianos, guitars, wind instruments, percussion and effects accessible from a simple interface.
We can edit any parameter of each instrument: the envelope (attack, decay, and release), the velocity, pitch and sending of effects.
If you're looking for a simple module, that has all kinds of instruments so that you can play your favorite songs thanks to your MIDI keyboard, Virtual Piano is probably what you were looking for.