  We present the results from the first two years of the Planet Hunters NGTS
citizen science project, which searches for transiting planet candidates in
data from the Next Generation Transit Survey (NGTS) by enlisting the help of
members of the general public. Over 8,000 registered volunteers reviewed
138,198 light curves from the NGTS Public Data Releases 1 and 2. We utilize a
user weighting scheme to combine the classifications of multiple users to
identify the most promising planet candidates not initially discovered by the
NGTS team. We highlight the five most interesting planet candidates detected
through this search, which are all candidate short-period giant planets. This
includes the TIC-165227846 system that, if confirmed, would be the lowest-mass
star to host a close-in giant planet. We assess the detection efficiency of the
project by determining the number of confirmed planets from the NASA Exoplanet
Archive and TESS Objects of Interest (TOIs) successfully recovered by this
search and find that 74% of confirmed planets and 63% of TOIs detected by NGTS
are recovered by the Planet Hunters NGTS project. The identification of new
planet candidates shows that the citizen science approach can provide a
complementary method to the detection of exoplanets with ground-based surveys
such as NGTS.
