Psychopy is a desktop application and python library for developing tasks (“games”), presenting stimuli. Though we have not taken advantage of the integration, psychopy links to the Amazon Turk alternative https://pavlovia.org/.
It's a free and open source alternative to EPrime, NeuroBS Presentation, and Millisecond Inquisit. The MATLAB alternative is Psychtoolbox.
Because psychopy and python are both open source, this is the preferred framework for building tasks.
Other pages that link here include tasks built with pyshcopy