Use arrow keys to control Mario, and WSAD keys to control Luigi. If you get stuck, use "r" to restart. You can play either Solo or Co-op. In Co-op, each player gets just 3 lives (as supposed to 5), but both must die in order for the level to restart. Watch out for bottomless pits, spinies, spikes, and lava!
Credit for RHY3756547 for the engine and several elements, I programmed some elements myself. Various sources for the sprites and sounds. UPDATE LOG: v1.0.5: A semi-working time limit system is up! Scary song when only 30 seconds remains!! D: V1.0.4: Four more levels in world 3, containing scary surprises! v1.0.3.1: One quarter of world 3 has been made. Yay? v1.0.3; Goombas were added. Also, world 2 has been finished. Now time for world 3.. v1.0.2.2: Added character differences. P2 can jump higher, but is a little slow. Mario had some changes. v1.0.2.1: No more dragging Mario/Luigi. v1.0.2: Fixed more bugs and finished the first half of world 2. v1.0.1: Fixed a few bugs. Added 1ups to the end of a world. Added just 2-1 so far.