The thing that holds the game back is its length.
In the battles, your party is running backwards away from hordes enemies. Your turns are taken by choosing to fire your current weapon, switching to another weapon, or using a consumable item. When choosing to attack, you choose your angle to aim. After you select your move, 5 seconds then play out in which you can move your characters up and down to dodge enemy fire, and to fire from a different position (you can't change your angle though, this must be done at the beginning of the turn). If you chose to switch weapon, a few seconds will pass before your character swaps to the new gun and begins firing at your specified angle.
New weapons are found throughout the levels, but additional weapons seem to be awarded randomly. The weapons are useful and it is often necessary to switch between them, given the type and number of enemies on screen.
The idea to mix real time and turn-based RPG elements definitely works well. The game-play mechanic and the amount of enemies on screen poses a great and satisfying challenge. The idea to mix Serious Sam with the RPG game style is a great one, and you expect a expect the high level of difficulty with the Serious Sam name put to it. Just like the main games, you can complete the levels with enough perseverance, luck and skill.
On each level, you have 3 lives. Losing a life just puts you back on the map, and losing all 3 lives throws you back to the start of the level, but you don't lose much progress due to the size of the maps.
The main campaign can be done under an hour, but its surprisingly enjoyable and challenging. An Endless Mode unlocks after you finish the final boss, but you won't last too long due to the difficulty of the game.
The simple graphics work well enough, and the game-play is only let down by the games' length. It is a great game but it seems as it was created as a bit of a joke which is why it is short. It would be amazing if it was a larger game with more ideas, but you can't complain too much given the budget price.