  We formulate Eddington's affine gravity in a spacetime which is immersed in a
larger eight dimensional space endowed with a hypercomplex structure. The
dynamical equation of the first immersed Ricci-type tensor leads to
gravitational field equations which include matter. We also study the dynamical
effects of the second Ricci-type tensor when added to the Lagrangian density. A
simple Lagrangian density constructed from combination of the standard Ricci
tensor and a new tensor field that appears due to the immersion, leads to
gravitational equations in which the vacuum energy gravitates with a different
cosmological strength as in Phys. Rev. D {\bf 90}, 064017 (2014), rather than
with Newton's constant. As a result, the tiny observed curvature is reproduced
due to large hierarchies rather than fine-tuning.
