I see a window there... good! Is it facing north or which direction is it? Are the doors & trim throughout the house all dark brown? Light doors & trim would help alot. Lighter happy paint colors, such as butter yellow or limon walls would bring a sunny warm fresh feel to the room. Try some punchy colored feature walls as shown in Manon's above photo (thanks Manon). Get new furniture & some fun colored art & accessories, everything's looking very dated. Better lighting & a tall floor lamp that spreads light across the ceiling or corner. Lighter drapes (with grommets) down to the floor would help OR Roman shades or 2" faux wood blinds covering just the window would modernize the space and give you more wall space. New flooring in updated colors such as white-washed gray driftwood. Designate areas or stations in the room for different activities, such as floor games in one corner with colorful interlocking foam floor mats, comfie seating (bean-bag chairs) for movies in another area, table & chairs for table activities (coloring/puzzles/games/crafts), etc. Are your children boys or girls? That'll make a difference in what you choose and how you put it all together.

Actually, just reread a bunch of the tile places and they all say not to use in shower. Bummer - that's out. However would still love ideas on what to do around it and if anyone can think of a way to update the acrylic walls? Or maybe it won't be as bad with new fixtures/shower curtain in better lighting... fingers crossed... just trying to get ideas together.

I love LED lights because they brighten up a room with ease!

I cant imagine that tiles on concrete will be any colder than concrete alone. But the choice of colour may make a difference to the heat absorption qualities; dark tiles will absorb heat better than light coloured ones.