Inclined air showers (typically with zenith angles 𝜃 > 60◦) feature a large effective geometric
acceptance, a high energy threshold, and broad sky coverage, making them a primary avenue for
ultra-high-energy cosmic ray (UHECR) and high-energy neutrino astronomy. However, traditional
inclined shower detection relies on large-scale arrays covering hundreds of square kilometers.
Small or compact arrays—such as LHAASO and the SKA-Low core—face severe challenges
in parameter reconstruction (e.g., primary energy, arrival direction, particle type, and 𝑋max) for
inclined events. Integrating recent breakthroughs, this paper systematically reviews advances in
inclined air shower detection, focusing on novel radio emission mechanisms, bi-effect magnetic
deflection models for secondary particles, and multi-observable reconstruction algorithms (electric
field, direction, energy, wavefront, etc.). Finally, we outline key challenges in event reconstruction
for ultra-dense and small-scale arrays.