The solo mode is the central hub for your single-player experience: split into gates, each incorporating a general theme. The first gate, Duel Strategy, is comparatively a tutorial extension to introduce more gameplay fundamentals: synchronization, link monsters, pendulum summoning, etc. and for new players, completing this gate helps you catch up to the modern-day game mechanics in Yu-Gi-Oh!, which is what we recommend as one of the first stops before heading to ranked.