As applications and especially games are moving to the web and mobile environments, different tools are needed to design these applications and their behavior. HTML5 in combination with JavaScript is a promising basis for such applications on a wide range of platforms. Content producers and designers often lack the tools for such developments, or the expertise to operate existing, but too complex tools. This paper presents work in progress about a novel domain-specific language (DSL) PULP that aims at closing this gap. The language allows tying content such as images and media files together by modeling the dynamic behavior, movements, and control flow. The DSL helps abstracting from asynchronous JavaScript, state machines, and access to cross-platform media playback, which is generated in a final model-to-text transformation. The DSL and tooling were created and evaluated in close cooperation with content authors.