  The progressive development of high power lasers over the last several
decades, enables the study of $\gamma$-photon generation when an intense laser
beam interacts with matter, mainly via inverse Compton scattering at the high
intensity limit. $\gamma$-ray flashes are a phenomenon of broad interest,
drawing attention of researchers working in topics ranging from cosmological
scales to elementary particle scales. Over the last few years, a plethora of
studies predict extremely high laser energy to $\gamma$-photon energy
conversion using various target and/or laser field configurations. The aim of
the present manuscript is to discuss several recently proposed $\gamma$-ray
flash generation schemes, as a guide for upcoming $\gamma$-photon related
experiments and for further evolution of the presently available theoretical
schemes.
