Research on rockfalls and prevention of the associated damages is becoming increasingly important and active particularly due to the often climate-change- or earthquakeinduced rock fragmentation in mountainous regions. Application of novel numerical methods on rock-tree/forest interactions simulation is an important part of the rockfall dynamics modelling, because understanding these issues would potentially improve the counter-measures management and hazards mitigation levels. Hence in this work the non-smooth mechanics coupled with hard contact laws is for the first time applied on modelling (non-)spherical rock-tree/forest impacts. The aim of this study is to probe and thus better understand from a fundamental level the role of rock shape in its energy dissipation during colliding with tree(s). The major findings are: (1) spherical and cubic rocks lose relatively more energy (in particular translational energy) than flat and long rocks within all impact regimes; (2) depending on the impact regime non-spherical rocks gain either stronger or weaker reflected rotation than a spherical rock; (3) rock rotational energy acts as an energy reservoir potentially influencing the impact-induced energy loss affected by rock shape and impact regime. Simulations of rockfalls along an ideally inclined virtual slope with forest cover demonstrate that rock shape dominates the entire energy dissipating process and consequently the run-out zone for these rocks.