Crate Pseudocode

Player
{
    update()
    {
        // ...
        if ( bumped into a solid )
        {
            velocity = 0;
            if ( bumped into CratePlaceholderBlock )
            {
                CratePlaceholderBlock crate = ( CratePlaceholderBlock ) tile bumped into;
                crate.crate.bump( side bumped into );
            }
        }
        // ...
    }
}

CratePlaceholderBlock
{
    CrateEntity crate;
    isSolid() { return true; }
}

CrateEntity
{
    Map< Position, Block > oldBlocks;
    update()
    {
        // ...
        // Similar code to what player has - Maybe common entity code?
        for ( every tile the crate overlaps right now )
        {
            Block block = level.getBlockAt( ... );
            if ( !( block instanceof CratePlaceholderBlock ) )
            {
                level.setBlockAt( ..., new CratePlaceholderBlock( this ) );
                oldBlocks.put( ..., block );
            }
        }
        for ( everything in oldBlocks )
        {
            Block block = ...;
            if ( no longer overlapping that block )
            {
                level.setBlockAt( ..., block );
            }
        }
        // ...
    }

    draw()
    {
        // Draw everything in oldBlocks so things don't flicker
    }

    bump( Side side )
    {
        if ( opposite side does not have solid tile )
        {
            velocity = ...;
        }
    }
}