According to the sell copy for Turning the Tide, in January 1945 "The Nazis' march towards total world domination is gathering pace". Which should tell you right off the bat this is an arcade shmup, evidently created by people who are historically illiterate. (The turning point was in 1942, with Stalingrad and Midway; in January 1945, the Bulge is extinguishing the Germans' last hope of stopping the Western Allies, the Russians are rolling relentlessly toward Berlin, and the Japanese are beginning to starve.)
In most of the game's 14 levels (4 in the demo), you're flying a plane (in some running a sub), with a wide variety of enemies and objectives -- mostly bombing missions of one kind or another, but some based mainly on shooting down enemy aircraft. A flight sim this is not; it's a sidescrolling shmup, with somewhat retro pixellated graphics but nice responsiveness.
What either makes the game interesting or makes it frustrating, depending on your attitude, is the control scheme; holding the left mouse button down increases your altitude, while releasing it puts you into a dive, so maintaining level flight means tapping the button in a particular rhythm. In the meantime, you're using other controls -- right mouse button to shoot, space to drop bombs, "a" and "d" to increase or decrease speed -- and keeping it all working requires practice and dexterity. As shmups go, it's less frantic than many, but the contrariness of the control system suffices to prevent it from being trivially easy for serious shmuppers.