Shihāb al-Dīn al-Suhrawardī (d. 1191), founder of the Islamic Illuminationist tradition, is one of the most controversial and misunderstood Arabic philosophers. Corbin cultivates Suhrawardī as a mystic who revived ancient Persian wisdom; Gutas reads him as a follower of Avicenna (d. 1037); scholars like Ziai and Walbridge argue that he is an original and serious philosopher. But it seems that no reconstructions of Illuminationist philosophy are satisfactory. I propose a Cave Story approach, which relates Suhrawardī's ambitious Illuminationist project to Plato's cave allegory. By following this approach, I present a historical reconstruction of Suhrawardī's Illuminationist philosophy, focusing on three areas: presential knowledge (epistemology), mental considerations (ontology and the problem of universals), and light metaphysics. Chapter I proves, by solid textual evidence, that Suhrawardī's four Peripatetic works and 'Ḥikmat al-Ishrāq' ('The Philosophy of Illumination', his masterpiece and the only Illuminationist work) constitute one and the same Illuminationist project. Chapter II reconstructs Illuminationist presential knowledge, an original epistemology of particulars (without any universals involved) and the epistemological foundation of Illuminationism. Chapters III and IV prove philosophically that universals must all be mental considerations (i.e. things created by the mind), and real things must be particulars; this is Suhrawardī's fundamental criticism of Peripatetic metaphysics. Chapter V reconstructs light metaphysics, a serious metaphysics of particulars (not universals). I conclude that Suhrawardī is an original and serious philosopher, who resorts to mysticism only for sound philosophical reasons, and who should not be taken as a follower of Avicenna; his Illuminationism is a philosophy of particulars rather than universals.