Not sure if serious? There were plenty of Semiautomatic weapons in WW1.
No there weren't. Not on an infantry level. There were machine guns, but grunts carrying semiautomatic weapons would have been pretty rare, and if/when encountered (if ever) there wouldn't have been hundreds of people all clustered with them on both sides like that game depicts.
Early semis were crappy, and quickly stopped running when they got dirty and/or dry, which is a bit of a problem when laying in dirt 24 hours a day in trench warfare. They were also crazy expensive and very slow to manufacture for the time. I think the French did it first (not 100% on that) at the very end of WWI, but production was
extremely limited due to the complexity and few were made.
For all intents and purposes, the first semiautomatic rifle commonly used as a standard troop weapon was the M1, by America in WWII. Even then, it took several years for them to get significant production going, so at the beginning of WWII, a lot of Americans carried the M1903 (the US sniper's rifle in
Saving Private Ryan) because they didnt have enough M1s. I own a relatively early 5-digit M1 (64,xxx) which is September 1940, but production started in mid-1937. I also own a 3,4xx,xxx which is December 1944. So in the first three years we made 64k, and in the next four years they made 3.5 Million!
EDIT: The short version is, even in WWII over 20 years later, America was the only nation that armed its' troops with a semiautomatic rifle on any significant level. The Russians wanted to, but they couldnt make enough as it was a complicated manufacture, especially after Germany invaded, so their troops relied on the bolt-action Mosin-Nagant.