This game uses two dice.
賽 is an old-fashioned, literary word for a die, while サイコロ is the common everyday term used in games and gambling.
monetary offering; offertory
Standard kanji for 'dice' in formal or literary contexts. This sense is formal/literary.
Rarely used kanji form for 'dice'.
Rarely used kanji form for 'dice'.
The kanji 賽 is used for its meaning related to dice. The reading さい is a Sino-Japanese reading. The word is a formal/literary term, while the more common サイコロ is of uncertain origin, possibly from 采 (さい) + 子 (ころ).