With biodiversity being lost at unprecedented rates, mitigating the impacts of development projects is a growing concern. International best practice indicates that projects located in natural habitats must achieve no net loss of biodiversity, or preferably a net gain. To do so, when development projects generate impacts on biodiversity that could not be sufficiently avoided or reduced, offsets must be designed and implemented to effectively and fully compensate for the residual loss of biodiversity, by generating measurable conservation gains elsewhere. There are considerable technical and organizational challenges to designing and implementing biodiversity offsets, which must also respect the legal and customary rights of local populations. Offset frameworks have been put in place in several countries worldwide but, in many circumstances, it is financial institutions and multinational companies that require these approaches as part of their risk management strategies. As such, they represent an important external influence on the future of tropical forested landscapes. A further challenge, however, is that developing countries, eager to access their natural resources, don't all share this ambition. We illustrate this with mining development in the tropical forest landscape which straddles the borders of Cameroon, Gabon and the Republic of Congo. Conservationists fear that the infrastructure being built to service an emerging iron ore province will reduce a large intact forest landscape to a mosaic of isolated protected areas no longer fit to conserve its mega-fauna or maintain large scale ecosystem processes. We use companion modelling techniques to build a model of the socio-ecological system, and develop future scenarios. In doing so, we map the role of various actors in making these futures possible. A key conclusion is that managing the impacts of mining development requires a strategic and multi-sectorial landscape-level approach, rather than dealing with eac