  We present GECKOS (Generalising Edge-on galaxies and their Chemical
bimodalities, Kinematics, and Outflows out to Solar environments), a new ESO
VLT/MUSE large program. The main aim of GECKOS is to reveal the variation in
key physical processes of disk formation by connecting Galactic Archaeology
with integral field spectroscopic observations of nearby galaxies. Edge-on
galaxies are ideal for this task: they allow us to disentangle the assembly
history imprinted in thick disks and provide the greatest insights into
outflows. The GECKOS sample of 35 nearby edge-on disk galaxies is designed to
trace the assembly histories and properties of galaxies across a large range of
star formation rates, bulge-to-total ratios, and boxy and non-boxy bulges.
GECKOS will deliver spatially resolved measurements of stellar abundances,
ages, and kinematics, as well as ionised gas metallicities, ionisation
parameters, pressure, and inflow and outflow kinematics; all key parameters for
building a complete chemodynamical picture of disk galaxies. With these data,
we aim to extend Galactic analysis methods to the wider galaxy population,
reaping the benefits of detailed Milky Way studies, while probing the diverse
mechanisms of galaxy evolution.
