  Play-to-earn is one of the prospective categories of decentralized
applications. The play-to-earn projects combine blockchain technology with
entertaining games and finance, attracting various participants. While huge
amounts of capital have been poured into these projects, the new crypto niche
is considered controversial, and the traditional gaming industry is hesitant to
embrace blockchain technology. In addition, there is little systematic research
on these projects. In this paper, we delineate play-to-earn projects in terms
of economic & governance models and implementation and analyze how blockchain
technology can benefit these projects by providing system robustness,
transparency, composability, and decentralized governance. We begin by
identifying the participants and characterizing the tokens, which are products
of composability. We then summarize the roadmap and governance model to exposit
there is a transition from centralized governance to decentralized governance.
We also classify the implementation of the play-to-earn projects with different
extents of robustness and transparency. Finally, we discuss the security &
societal challenges for future research in terms of possible attacks, the
economics of tokens, and governance.
