Nay,

Halo1, new engine
Halo2, newer engine
Halo3, newer engine
Halo3:ODST, modified Halo3 engine
Halo Reach, newer engine

Halo Reach was Halo4. Halo4 is actually still Halo4, 343i is just trollin' about some new trilogy. Kinda like Lucas and the Prequels.