Insurmountable is a strategic adventure game that combines roguelike elements with an engaging mountaineering experience. Players embark on a challenging journey through randomly generated terrains of Ice, Snow, and Stone, where they must navigate the unpredictable weather and day-night cycles. The game emphasizes risk management as players utilize items to maintain their character's diminishing stats while climbing the treacherous mountain. With each ascent, players encounter various events that test their survival skills, making every playthrough unique.

Character improvement is central to the gameplay, as players earn experience points to unlock skills tailored to their preferred playstyle. The presence of permadeath introduces a significant challenge, encouraging players to experiment with different strategies to reach the summit. Insurmountable not only focuses on decision-making in a perilous environment but also seeks to evoke the intense emotions associated with extreme adventures in nature.