Complex sentence: Repeating request from bond graph researchers made the University of Twente start the development of a successor of TUTSIM resulted in the software 20-sim, which contains many of the features that made TUTSIM popular.
Split into simpler sentences: Repeating request from bond graph researchers made the University of Twente start the development of a successor of TUTSIM. This resulted in the software 20-sim, which contained many of the features that made TUTSIM popular.