All free online games or drills. Some ads. I manipulate the screen to avoid them or stay with my child to avoid as necessary.
MATH
Algebra from My Drills: Linear equations, linear equivalents, linear systems, polynomials, complex numbers, quadratic equations, sequences and series
Arithmetic from My Drills: Math practice online for addition, subtraction, multiplication, and division up through number 9
Math Facts from Easy Peasy All-in-One Homeschool: List of online math practice resources for addition, subtraction, and multiplication
Merge Dice from Toy Theater: Number game to combine numbers
Nonogram from Toy Theater: Playing with number patterns
Pre-algebra from My Drills: Drills on all kinds of math facts including whole numbers, factors and multiples, integers, fractions, decimals, ratios and proportions, percents, exponents, radicals, linear equations, linear equivalents, linear systems