Complex sentence: They had some complaints regarding Ven's demo due to constant jumping, but further stated that Ven's demo gave them an idea of "how the game is going to feel", and predicted the game would improve the series.
Split into simpler sentences: They had some complaints regarding to Ven's demo due to constant jumping. They further stated that Ven's demo gave them an idea of "how the game is going to feel", and predicted the game would improve the series.