Here is a pseudo-code algorithm designed to calculate the forecasted server load scaling for an online platform over a 5-hour launch window.

2  # Expected loads over 5 hours post-launch
3  SET hourNumber TO ["+1", "+2", "+3", "+4", "+5"]
4  SET loadScaling TO [115, 130, 145, 160, 180]
5  SET goodInput TO False
6
7  # Validate base load capacity
8  WHILE (goodInput = False) DO
9      SEND "Enter the baseline server capacity (min 500): " TO DISPLAY
10     RECEIVE baseCapacity FROM (INTEGER) KEYBOARD
11
12     IF (baseCapacity >= 500) THEN
13         SET goodInput TO True
14         SEND "Baseline capacity recorded: " & baseCapacity TO DISPLAY
15     ELSE
16         SEND "Invalid baseline capacity" TO DISPLAY
17     END IF
18 END WHILE
19
20 # Calculate hourly scaling requirements
21 FOR i FROM 0 TO (LENGTH(hourNumber)-1)
22     SET scaleFactor TO loadScaling[i] / 100
23     SET forecastedLoad TO baseCapacity * scaleFactor
24     SEND "Hour " & hourNumber[i] & " forecast: " & forecastedLoad TO DISPLAY
25 END FOR