Good action game, surprisingly long for for an online game, but there should be a save feature. I downloaded the game and there still was no option to save progress. The game is rather long to finish in one sitting which is good, but lack of save feature forces player to find a window with lot of time to finish this.
The enemies are fun and challenging, diffuculty progression from first to last levels is fluent, but the bosses are somewhat dissapointing not intresting enough and too easy.
Also I could not find any actual difference between difficulty levels, damage taken, enemy density and toughness, ammo - all seemed the same.