There is a SRD for 5.0. Incarna reflected the “gritty realism” (see 5th Edition DMG p.) perspective and lethality missing in the common tropes most often presented in ©Dungeons and Dragons™. The HP and AC mechanics were really no more than an endless pursuit of pluses and adjustments. With 5th edition, many of these approaches are defined variants and now work well in a balanced DnD system. The “Incarna D20 Branch” (originally begun in 08/2015 – see original work & original announcement) is a branch of the Incarna game which incorporates D20 rules with a set of custom guidelines (essentially a “home brew“) to produce a custom variant. Incarna is proud to also stand as a still fully independent and unique approach (“Incarna Core”) among many independent game builders.