I am looking for examples of games that are subject of research in both fields of game theory and Combinatorial game theory. Does a game that was the subject of a research in both fields exists?
From what I have read, CGT limits the focus to two-player games of perfect information, alternating moves, and no chance. I think that GT have no limitations on games features.
In a different question it is said that there is little to no connection between the fields. If I would to research a game from both fields, what would be the difference in the research questions?
There really aren't such games. GT from the start concentrates on uncertainty and iterated play and equilibria and its motivating examples are sociological/economical (already in Von Neumann and Morgenstern's seminal work "Theory of Games and Economic Behavior"), very much in a mathematical economics framework (utitily and pay-off functions etc.). CGT came more from mathematics (Zermelo being an early example, and of course Conway et al) and wants to solve games where all is known in advance, leading to "nimbers" and surreal numbers etc.
Their "flavour" is very different. GT studies different kinds of equilibria, and what happens if players deviate from them etc. You cannot really do both at the same time, and not many people have even tried, that I have seen. GT focuses on the player, CGT on the game.