Ranks are a cosmetic game mechanic in Critical Strike Portable and Critical Ops. Ranks are a way to indicate a player's status, although this is represented differently between both Critical Strike Portable and Critical Ops.
In Critical Strike Portable, they are determined by the player's kill/death ratio and in Critical Ops, they are determined by how many total ranked games a player wins or loses and are only attainable after the player has reached 250 kills.
These have no real gameplay advantages or disadvantages whatsoever, other than for cosmetic use.
Ranks are earned through playing ranked games, which are accessible through the main menu and only if the player reaches 250 kills. In order for a player to rank up, they must earn 15 points from winning matches, which consist of 9 total rounds won (unlike casual which consists of 13). The opposite can also occur, so if a player happens to lose enough rounds, they will lose points and rank down.
For unranked players, a total of 10 placement matches must be won. After ranking up, the player will be assigned a rank, depending on the amount of wins to losses.
Critical Strike Portable
Ranks label a player's kill to death ratio, and gives a general idea on their skill. The higher the kill count than the death count the lower the rank. Higher ranks are determined by lower numbers, so for example, the highest rank a player can attain is 1, and the lowest (and initial) rank is 64.
In order to rank up, a player must improve his/her kill/death ratio by killing players more often than dying. Dying more than killing will cause the player to rank down.