Some BASIC fun

DIM wellWidth AS UBYTE = 10   REM Well width in characters
DIM wellHeight AS UBYTE = 20  REM Well height in characters
DIM shapeRow AS UBYTE = 0     REM Shape's top row
DIM shapeCol AS UBYTE = 4     REM Shape's left column
DIM shapeWidth AS UBYTE = 2   REM 2x2 square shape
DIM shapeHeight AS UBYTE = 2
DIM gameOver AS UBYTE = 0

REM Initialize screen and well
CLS
REM Set well background attributes to 0 (black)
FOR row = 0 TO wellHeight - 1
    FOR col = 0 TO wellWidth - 1
        POKE (22528 + row * 32 + col), 0
        PRINT AT row, col; " "  REM Clear display
    NEXT col
NEXT row
REM Draw well borders (optional, for visibility)
FOR row = 0 TO wellHeight - 1
    PRINT AT row, wellWidth; "|"
    POKE (22528 + row * 32 + wellWidth), 6  REM Yellow border
NEXT row
PRINT AT wellHeight, 0; STRING$(wellWidth, "-")
FOR col = 0 TO wellWidth - 1
    POKE (22528 + wellHeight * 32 + col), 6
NEXT col

REM Main game loop
DO WHILE gameOver = 0
    REM Draw shape (2x2 square)
    FOR r = 0 TO shapeHeight - 1
        FOR c = 0 TO shapeWidth - 1
            PRINT AT shapeRow + r, shapeCol + c; CHR$ 143
            POKE (22528 + (shapeRow + r) * 32 + shapeCol + c), 7
        NEXT c
    NEXT r

    REM Handle input
    IF INKEY$ = "q" AND shapeCol > 0 THEN
        LET shapeCol = shapeCol - 1  REM Move left
    ELSE IF INKEY$ = "p" AND shapeCol + shapeWidth < wellWidth THEN
        LET shapeCol = shapeCol + 1  REM Move right
    ELSE IF INKEY$ = "a" THEN
        LET shapeRow = shapeRow + 1  REM Move down faster
    END IF

    REM Check collision below
    LET collision = 0
    IF shapeRow + shapeHeight >= wellHeight THEN
        LET collision = 1  REM Hit bottom
    ELSE
        FOR c = shapeCol TO shapeCol + shapeWidth - 1
            LET attrAddr = 22528 + (shapeRow + shapeHeight) * 32 + c
            IF PEEK(attrAddr) <> 0 THEN
                LET collision = 1
                EXIT
            END IF
        NEXT c
    END IF

    REM Move shape down or stop
    IF collision = 0 THEN
        LET shapeRow = shapeRow + 1
    ELSE
        REM Stop shape, check for game over
        IF shapeRow = 0 THEN
            LET gameOver = 1
            EXIT
        END IF
        REM Check for completed rows
        GOSUB checkRows
        REM Spawn new shape
        LET shapeRow = 0
        LET shapeCol = 4
    END IF

    REM Clear previous shape position
    FOR r = 0 TO shapeHeight - 1
        FOR c = 0 TO shapeWidth - 1
            PRINT AT shapeRow + r - 1, shapeCol + c; " "
            POKE (22528 + (shapeRow + r - 1) * 32 + shapeCol + c), 0
        NEXT c
    NEXT r

    PAUSE 10  REM Slow down for playability
LOOP

PRINT AT 10, 2; "Game Over"
STOP

checkRows:
REM Check each row of the shape for completion
FOR r = shapeRow TO shapeRow + shapeHeight - 1
    LET complete = 1
    FOR c = 0 TO wellWidth - 1
        IF PEEK(22528 + r * 32 + c) = 0 THEN
            LET complete = 0
            EXIT
        END IF
    NEXT c
    IF complete = 1 THEN
        REM Shift rows down
        FOR row = r TO 1 STEP -1
            FOR col = 0 TO wellWidth - 1
                LET attrAbove = PEEK(22528 + (row - 1) * 32 + col)
                POKE (22528 + row * 32 + col), attrAbove
                PRINT AT row, col; " "
                IF attrAbove <> 0 THEN
                    PRINT AT row, col; CHR$ 143
                END IF
            NEXT col
        NEXT row
        REM Clear top row
        FOR col = 0 TO wellWidth - 1
            POKE (22528 + col), 0
            PRINT AT 0, col; " "
        NEXT col
    END IF
NEXT r
RETURN