Requirements engineering for complex systems often requires inter-disciplinary collaboration between domain experts who might not have software or systems engineering background. Existing requirements modeling languages unfortunately do not support this scenario well. First, the visual notation of languages like UML or SysML does not follow scientific heuristics and therefore does not provide a homogeneous and more important interdisciplinary comprehensible visualization. Second they provide isolated solutions for specific aspects like feature modeling or hazard modeling and therefore do not provide integrated and interdisciplinary traceability. We propose the Unified Requirements Modeling Language (URML) to overcome these two issues. URML integrates aspects like goal modeling, feature modeling and hazard analysis into one model and aims at a homogeneous and comprehensible visualization. In this paper we propose the meta-model for URML, describe the development of the corresponding visualization as well as initial tool support.