Many no-name LCD games seem to be based on the documented Holtek HT1130 4-bit microcontroller. On websearch I didn't found them mentioned although IC datasheets are available. Are they already emulated?

HT1130 4-bit Microcontroller.pdf

HT113AA 2Streetfighters2 LCD Game.pdf
HT113FA Submarine War LCD Game.pdf
HT113JA Baseball LCD Game.pdf
HT113LA Mini Brick LCD Game.pdf
HT113RA Poker and Black Jack LCD Game.pdf
HT113SA Casino Game 5-in-1 LCD Game.pdf
HT1132A SPACE WAR LCD Game.pdf
HT1134A Pin Ball LCD Game.pdf
HT1136A Football LCD Game.pdf
HT1137A Motorcycle LCD Game.pdf
HTG1395 3-in-1 LCD Game.pdf

Holtek (Taiwan) is one of the biggest manufacturer of cheap button cell operated LCD gadgets, and also seems to be the hidden creator behind many no-name single chip keyboard CPUs, including some of the most exciting mini keyboard LSI with multipulse squarewave and great POKEY-style blip percussion (like EK-001 and Creatoy). Also My Music Center variants (sound engine "Ad-lib Micro®") and many modern Yongmei grade COB chips (e.g. 100 preset sounds + LED display etc.) seem to be their creation (functions seen in datasheets). While official Holtek chips have the naming convention HT + number (+ optional letter + number for software version), also many rebranded versions with different naming can be found. With single chip mini and toy keyboards Holtek was in late 1990th at least among the big 3 next after Casio and Yamaha (in sold units count likely even higher). Because those cheap toy tablehooter chips often have resistor controlled clock rate with poorly stabilized voltage that changes pitch with empty batteries, they also got their nickname "Howltek".