  The suppression of superconductivity in disordered systems is a fundamental
problem of condensed matter physics. Here we investigate the superconducting
niobium-titanium-nitride (Nb_{1-x}Ti_{x}N) thin films grown by atomic layer
deposition (ALD) where disorder is controlled by the slight tuning of the ALD
process parameters. We observe the smooth crossover from the disorder-driven
superconductor-normal metal transition (often reffered to as fermionic
mechanism) to the case where bosonic mechanism dominates and increasing
disorder leads to formation of metal with Cooper pairing. We show that, in
moderately disordered films, the transition to zero-resistance state occurs in
a full agreement with the conventional theories of superconducting fluctuations
and Berezinskii-Kosterlitz-Thouless transition. However, the critically
disordered films violate this accord showing low-temperature features possibly
indicating the Bose metal phase. We show that it is the interrelation between
film's sheet resistance in the maximum, R_{max}, of the resistive curve R(T)
and R_q = h/4e^2 that distinguishes between these two behaviors. We reveal the
characteristic features in magnetoresistance of the critically disordered films
with R_{max} > R_q
