Order of Operations Millionaire Game:

http://www.math-play.com/Order-of-Operations-Millionaire/order-of-operations-millionaire.html 

Rounding Decimals Games:

http://www.abcya.com/rounding_numbers.htm (Choose level 3)

http://www.sheppardsoftware.com/mathgames/decimals/scooterQuestDecRound.htm 

Comparing Decimals Game: 

http://www.abcya.com/comparing_number_values.htm (Choose DECIMALS)

Measuring and Conversion Games:

http://www.sheppardsoftware.com/mathgames/menus/measurement.htm 

Adding Decimals:

 https://www.education.com/game/decimal-weight-addition/

Decimals with Models: 

https://www.splashmath.com/math-skills/fifth-grade/decimal-arithmetic/add-decimalsals

Multiplying Decimals:

https://www.splashmath.com/math-skills/fifth-grade/decimal-arithmetic/multiply-decimals-by-a-whole 

Quadrilaterals: 

http://www.sheppardsoftware.com/mathgames/geometry/shapeshoot/QuadShapesShoot.htm