  Over the past few years, wide-field time-domain surveys like ZTF and OGLE
have led to discoveries of various types of interesting short-period stellar
variables, such as ultracompact eclipsing binary white dwarfs, rapidly rotating
magnetised white dwarfs (WDs), transitional cataclysmic variables between
hydrogen-rich and helium accretion, and blue large-amplitude pulsators (BLAPs),
which greatly enrich our understandings of stellar physics under some extreme
conditions. In this paper, we report the first-two-year discoveries of
short-period variables (i.e., P<2 hr) by the Tsinghua University-Ma Huateng
Telescopes for Survey (TMTS). TMTS is a multi-tube telescope system with a
field of view up to 18 deg^2, which started to monitor the LAMOST sky areas
since 2020 and generated uninterrupted minute-cadence light curves for about
ten million sources within 2 years. Adopting the Lomb-Scargle periodogram with
period-dependent thresholds for the maximum powers, we identify over 1 100
sources that exhibit a variation period shorter than 2 hr. Compiling the light
curves with the Gaia magnitudes and colours, LAMOST spectral parameters, VSX
classifications, and archived observations from other prevailing time-domain
survey missions, we identified 1 076 as delta Scuti stars, which allows us
study their populations and physical properties in the short-period regime. The
other 31 sources include BLAPs, subdwarf B variables (sdBVs), pulsating WDs,
ultracompact/short-period eclipsing/ellipsoidal binaries, cataclysmic variables
below the period gap, etc., which are highly interesting and worthy of
follow-up investigations.

Solar and Stellar Astrophysics;High Energy Astrophysical Phenomena;Instrumentation and Methods for Astrophysics