The researchers developed a new solution concept called Complete Sequential Equilibrium (CSE) for games with observed actions. CSE is always a Nash equilibrium and is equivalent to the existing concept of Sequential Equilibrium (SE) in finite games. They also introduced an alternative solution concept called Weak CSE (WCSE), which is a simpler version of CSE. Both CSE and WCSE are complete solution concepts for general games. The relationship between these concepts and other equilibrium concepts is explored in the article.