1950

1950 arrived with the 1.07.0 update for Pump It Up 2015 PRIME and immediately took the throne as the arcade boss song. It was written by MAX, here credited under the alias SLAM. The title's meaning was never explained: because the BGA (by YSJ) is packed with death imagery, including a grim reaper and graves, some speculated it referenced the Korean War, but nato shut that theory down on Twitter. The song became playable in Japan on December 30, 2015 with version 1.08.0, and in Pump It Up M it unlocks as a reward after 21 days of attendance. It belongs to the numeric 19XX series, later continued by 1949 in XX and 1948 in PHOENIX.

The community expected a high-level but unremarkable 200 BPM song. When the Double level 27 chart surfaced, chaos broke out: many judged it harder than the then-feared Chimera and Cleaner charts, and even tougher than the Vacuum Cleaner D27 that held the crown. At the same time the S25 dethroned Vacuum Cleaner's S25 as the Single final boss, making 1950 the undisputed final boss song among Prime's debuts. The D27 was the series' second official D27 and the first in arcade mode; it lost the top-level crown once PARADOXX arrived, and handed off the arcade's hardest-difficulty title to its successor 1949 in XX. FEFEMZ* claimed the world's first break-on of the D27 on September 20, 2015, with 24 misses.

The original launch charts (S23, S25, D25 and D27) were all built by WINDFORCE, the 2009 amateur e-sports champion. Later additions included EXC's S20 and HUCAR's DP03 Performance chart. The S16 came from a UCS contest and was made by OSING (credited as Daeguosu through Prime 2); with honest trills and bursts at high BPM, it doubles as good practice for processing fast streams. The D22 was the work of US player ZELLLOOO, also a UCS contest winner. In XX both the punishing S25 and the D27 were nerfed with a focus on gauge management. Prime 2's Quest Zone offered S21 and D22 versions subtitled Conrad's Nanta, with the quirky clear condition of surviving more than 1950 steps.